aps - Physics · Plastic container and lid. Steel, plastic, wooden spheres Transparency sheet. Tissue paper Plastic box. Pipette with rheoscopic fluid concentrate Black construction

learn how your world workscomWritten by

Rebecca Thompson, Ph.D.

Illustrated byKerry G. Johnson

American Physical Society © 2013

All Rights Reserved

MARCH • 2013

www.aps.org

TM

PhysicsQuest: Spectra -Turbulent Times!

Written by Rebecca Thompson, Ph.D.

Illustrations by Kerry G. Johnson

PhysicsQuest: Spectra - Turbulent Times! - Issue #5 Published by the American Physical Society

American Physical Society © 2013 – All Rights Reserved

Printed in the U.S.A.

TM

WELCOME TO PHYSICSQUESTHistory of the PhysicsQuest ProgramAs part of the World Year of Physics 2005 celebration, the American Physical Society (APS Phys-ics) produced PhysicsQuest: The Search for Albert Einstein’s Hidden Treasure. Designed as a re-source for middle school science classrooms and clubs, the quest was received enthusiastically by nearly 10,000 classes during the course of 2005. Feedback indicated that this activity met a need within the middle school science community for fun and accessible physics material, so the American Physical Society has decided to continue this program. APS is pleased to present this eighth kit, PhysicsQuest: Spectra - Turbulent Times.

In the past, each PhysicsQuest kit has followed a mystery-based storyline and requires students to correctly complete four activities in order to solve the mystery and be eligible for a prize drawing. For the fourth year in a row students will be following laser superhero Spectra. Past years have seen the downfall of the evil Miss Alignment (Issue #2), the unfortunate demise of General Rela-tivity (#3) and the evil antics of “mean girl” Tiffany Maxwell’ Demon (#4). This year, the students will learn about fluid dynamics as they help Spectra try to stop her swim coach Henri Toueaux from destroying his team in an effort to beat the Thomas A. Edison Middle School Wizards of Menlo Park, IN in the state swim meet championship.

About the American Physical Society (APS Physics)APS is the professional society for physicists in the United States. APS works to advance and disseminate the knowledge of physics through its journals, meetings, public affairs efforts, and educational programs. Information about APS and its services can be found at www.aps.org. APS also runs PhysicsCentral, a website aimed at communicating the excitement and importance of physics to the general public. At this site, www.physicscentral.com, you can find out about APS educational programs, current physics research, people in physics and more.

About PhysicsQuestPhysicsQuest is a set of four activities designed to engage students in scientific inquiry. This year’s activities are linked together via a storyline and comic book that follows Spectra, a laser super hero and her battles with “mean girl” Tiffany Maxwell and her impish Demon. Spectra’s super power is her ability to turn into a laser beam. Her powers are all real things that a laser beam does so in addition to learning via the 4 activities students will also learn through the comic book.

PhysicsQuest is designed with flexibility in mind – it can be done in one continuous session or split up over a number of weeks. The activities can be conducted in the classroom or as an extra credit or science club activity. The challenges can be completed in any order, but to get the correct final result all of the challenges must be completed correctly.

On FacebookThere’s now a PhysicsQuest Facebook Group, that you may join to connect with other teachers and participants so that you can share and learn tips and trick. About the PhysicsQuest CompetitionAPS sponsors an optional PhysicsQuest competition designed to encourage students to invest in the project. If you chose to participate in the competition, your class must complete the four activities and you must submit their answers online by May 17th, 2012. All classes that submit answers online will receive a certificate of completion and be entered into a prize drawing. Details on the prizes will be posted on the PhysicsQuest website as they become available. The online results submission form does not require the answers to all of the questions on the Final Report. If your class only has time to complete some of the activities, they can still submit their an-swers, be eligible for prizes and receive a certificate of participation. Each class can only submit one entry form, so class discussions of results are encouraged. Answers can be submitted online through the PhysicsQuest website beginning March 25, 2013.

The PhysicsQuest MaterialsThe PhysicsQuest kit includes this manual and most of the hardware your students need to complete the activities. There is also a corresponding website, www.physicscentral.com/physicsquest, which has supplemental material such as extension activities. The comic bookEach activity will be preceded by several pages of a comic book that will follow the adventures of Spectra. The comic is also available online. Students will complete the activity and in the end they will need their answers to all four activities to help Spectra stop the coach from destroying the school.

The Materials ListFor more information on these items and where they can be purchased, please visit the PhysicsQuest website. If your kit is missing any of these materials, please contact Educational Innovations, www.teachersource.com or (203) 229-0730

Included in this kit:Plastic container and lidSteel, plastic, wooden spheresTransparency sheetTissue paperPlastic boxPipette with rheoscopic fluid concentrateBlack construction paperKetchup packets (2)Glass “sand”Plastic spoonTart pastry pans (4)Plastic bagRubber bandManual (Comic Book)

Not included in this kit:WaterScissorsPaper cupsBottle with lid (20-ounce soda bottle works best)Masking tapeThin bookPermanent markersIndex card

WELCOME TO PHYSICSQUEST

The Teacher Guide includes:· Key Question: This question highlights the goal of the activity. · Key TermsThis section lists terms related to the activity that the students will encounter in the Student Guide. · Before the Activity:Students should be familiar with these concepts and skills before tackling the activity. · After the Activity:By participating in the activity, students are practic-ing the skills and studying the concepts listed in this section. · The Science Behind…This section includes the science behind the activity, The Student Guide does not include most of this in-formation; it is left to you to decide what to discuss with your students. · SafetyThis section highlights potential hazards and safety precautions. · MaterialsThis section lists the materials needed for the activity. Materials that are provided in the kit are in bold type; you will need to provide the rest. · Extension ActivitiesExtension activities related to each activity can be found on the PhysicsQuest website. This section gives a brief description of those related to the activity. · Bibliography and Suggested ResourcesThis section lists resources used to create this activity and recommended resources for more information on the topics covered.

The Student GuideEach activity has a Student Guide that you will need to copy and hand out to all of the students.

The Student Guide includes:· Key QuestionThis question highlights the goal of the activity. · MaterialsThis section lists the materials students will need for the activity.

· Getting StartedThis section includes discussion questions designed to get students thinking about the key question, why it’s important, and how they might find an answer. · The ExperimentThis section leads students step-by-step through the set-up and data collection process. · Analyzing your ResultsThis section leads students through data analysis and has questions for them to answer based on their re-sults.

PhysicsQuest WebsiteThe PhysicsQuest website, www.physicscentral.com/physicsquest, has supplemental material for teachers, such as extension activities. Periodic updates on the program will also be posted on this site.

PhysicsQuest LogisticsMaterialsThe PhysicsQuest kit comes with only one set of ma-terials. This means that if your students are work-ing in four small groups (recommended), all groups should work simultaneously on different activities and then rotate activities, unless you provide addi-tional materials. The Materials List on the Physics-Quest website includes specific descriptions of the materials and where they can be purchased. All ma-terials can be reused. SafetyWhile following the precautions in this guide can help teachers foster inquiry in a safe way, no manual could ever predict all of the problems that might oc-cur. Good supervision and common sense are always needed. Activity-specific safety notices are included in the Teacher Guide when appropriate.


Time RequiredThe time required to complete the PhysicsQuest ac-tivities will depend on your students and their lab experience. Most groups will be able to complete one activity in about 45-minutes.

Small GroupsWorking effectively in a group is one of the most im-portant parts of scientific inquiry. If working in small groups is challenging for your students, you might consider adopting a group work model such as the one presented here.

Group Work ModelGive each student one of the following roles. You may want to have them rotate roles for each activity so they can try many different jobs. · Lab DirectorCoordinates the group and keeps students on task. · Chief ExperimenterSets up the equipment and makes sure the proce-dures are carried out correctly. · Measurement OfficerMonitors data collection and determines the values for each measurement. · Report WriterRecords the results and makes sure all of the ques-tions in the Student Guide are answered. · Equipment ManagerCollects all equipment needed for the experiment. Makes sure equipment is returned at the end of the class period and that the lab space is clean before group members leave.

PhysicsQuest in the ClassroomThis section suggests ways to use PhysicsQuest in the classroom. Since logistics and goals vary across schools, please read through the suggestions and then decide how best to use PhysicsQuest. Feel free to be creative! · PhysicsQuest as a stand-alone activityPhysicsQuest is designed to be self-contained – it can be easily done as a special project during the day(s) following a test, immediately preceding/following winter break, or other such times. PhysicsQuest also works well as a science club activity and extra credit opportunity. · PhysicsQuest as a fully integrated part of regular curriculumThe topics covered in PhysicsQuest are covered in many physical science classes, so you might have stu-dents do the PhysicsQuest activities during the cor-responding units. · PhysicsQuest as an all-school activitySome schools set up PhysicsQuest activity stations around the school gym for one afternoon. Then small groups of students work through the stations at as-signed times. · PhysicsQuest as a mentoring activitySome teachers have used PhysicsQuest as an oppor-tunity for older students to mentor younger students. In this case, 8th or 9th grade classes first complete the activities themselves, and then go into 6th or 7th grade classrooms and help students with the activi-ties.


SPLOSH ! !

P U B L I S H E D B Y T H E A M E R I C A N P H Y S I C A L S O C I E T Y © 2 0 1 3

TURBULENT TIMESWritten by Rebecca Thompson, PH.D. • Illustrated by Kerry G. Johnson

Everything has calmed down at Nikola Telsa Middle School for Lucy “Spectra” Hene and her friends since their adventure with Tiffany Maxwell and her Demon in Issue #4. Over the last few months, Lucy has managed to focus on her training with the swim team. We start this tale with Lucy

and her swimmates training at the Rose Bowl Aquatic Center in Pasadena, California.

C’MON CHARGERS!GET BACK IN THE WATEr!

YOU’VE GOT one more set. AFTER THAT, You ALL GET

to cool down.

You’ve ALL worked hard, but this one is going to

be rough. ARE you ready?

AWHH COACH! WE’RE TIRED! CAN WE TAKE A BREAK?

I THOUGHT I WAS TRAINING WINNERS, NoT WHINERS!

Remember, every time you whine, that’s another 100 METERS

added to your “whining” set.NOW GET READY.

3... 2... 1...

A-C! A-C! POWER LINES! TESLA BEATS YOU

EVERY TIME!

GO CHARGERS!

IT’s Easier for water to flow

around a triangle than a square,

so FORM yourselfInTO a triangle.

GO AGAIN.3 ... 2 ... 1 ...

THAT SET HURT!

I sure FELT like a barge,CERTAINLY not LIKEan airplane wing.

MINE Too, it’s likethe water WAS being

pushed back against us.

THAT just dIDN’t feel right And

my shoulders are

KILLING ME.

THAT WASN’T GooD ENOUGH!

EVERYBODY, Make sure when you’re

underwater, you look more like an airplane

wing than a barge.

BACK AT SCHooLI Know

GenERAL RELATIVITY*did an experiment in PHYSICS class

ON THIS TOPIC.

Lucy’s already exhausted, but she and the rest of the team manage to push themselves off the wall.

*General Leslie J. Relativity first appeared in Spectra #3: Force.

This year’s team is great. I think we CAN WIN IT ALL!

Back at the team’s hotel

I just need to push them a

little harder.

AS THE SWIM TEAM MANAGER YOU KNoW

I HAVE TO KeeP UP WITH EVERYONE’s TIMES. WHAT was

UP WITH THAT LAST SET? WHY DID YOU GUYS

SLOW DOWN ON THOSE LAST LAPS?

MAYBE WE CAN TALk THROUGH THIS STUFF

AFTER YOU STOP CHOMPING DOWN ALL

THAT JUNK FooD.

P H Y S I C S Q U E S T : S P E C T R A - T U R B U L E N T T I M E S ( I S S U E # 5 )

ACTIVITY 1 - A

ACTIVITY 1: Go With the FlowNOTE: Setting up this experiment can take a bit of time. If you have limited class time, set this up activity beforehand.

T E A C H E R G U I D E

INTROYou often see water flowing, but it is difficult to see how it flows. This experiment uses “rheoscopic fluid” to show how water flows around different shapes. KEy TERMSFluid: Anything that flows; both liquids and gases are fluids.

Rheoscopic fluid: A type of liquid that has tiny, ground-up fish scales suspended in water.

Flow: Movement of a fluid

Laminar (streamline or smooth) Flow: Fluid flows in one direction and doesn’t mix side to side

Turbulent (rough) Flow: As the fluid flows it mixes from side to side and can also create eddies

Hydrodynamic: How well a fluid flows by an object. If something is extremely hydrodynamic, fluid flows by it eas-ily.

Eddy: Swirls and mixing that happens when fluid flow is in-terrupted by an object. If an object isn’t very hydrodynamic, lots of eddies are formed.

MATERIALSn Pen box topn Pipette filled with rheoscopic fluidn Black construction papern Transparency n Sheet with rectanglesn * Bottle with lid (20 ounce soda bottle works well)n * Cupn * Adhesive tapen * Thin bookn * Watern * Permanent Markern * Scissors *Not included in the PhysicsQuest Kit

BEFORE THE ACTIVITY, STUDENT SHOULD KNOWn Fluids flow downhill.n The flow of a fluid changes when it encounters an object. n The shape of the object will affect how the flow changes.n Periodic motion means an object follows the same path repeatedly.

AFTER THE ACTIVITY, STUDENTS SHOULD BE ABLE TOn Define “laminar flow.” n List the shapes that allow water to easily flow and the shapes that are more difficult.n Explain why “hydrodynamic” object such as boats are shaped as they are.n Explain why Michael Phelps works on his streamline.

THE SCIENCE BEHIND flowing around an objectIf you’ve ever stuck your hand out of the window of a mov-ing car or watched Michael Phelps streamline underwa-ter on his way to win yet another gold medal, you already know a lot about how fluids flow. Think of a the shape of a Honda Element vs. a Corvette. Which one do you think moves through air more easily? You were probably able to answer these questions pretty quickly because we all have an intuitive understanding of how water and air flow. In this ex-periment you will get to see what happens when fluid flows around differently shaped objects.

Most times when water is flowing it is difficult to see exactly how it is flowing. However, it is possible to see how water flows using a special type of fluid called rheoscopic fluid. Rheoscopic literally means “current showing.” It is made up of tiny, shiny flat pieces that are good reflectors of light. Be-cause they are flat, the will point in the direction of the water (Fig. 1). They don’t mix with water the way dyes might so the fluid can be used over and over again. Often times these shiny pieces are made of ground up fish scales.

Water moves the most quickly if there is nothing in its way. When its flowing smoothly, or laminar flow, all the water is flowing in the same direction with no turbulence. If the water is flowing along and runs into an object, it’s going to slow down in order to flow around the object somehow. If the object doesn’t create much turbulence and the water is still flowing pretty smoothly, it’s not going to slow down too much. It doesn’t lose a lot of energy to eddies and so can keep going at roughly the same speed and it will still be close to laminar flow.

K E Y Q U E S T I O NWhich shapes are more hydrodynamic?

However, if the object creates a lot of eddies and turbu-lence, then the water is going to slow down a lot. Its flow will no longer be anywhere near laminar flow. The closer flow is to laminar, the faster it can go.

The opposite is also true. If you are trying to drag some-thing through water and it doesn’t create many eddies, then it doesn’t require a lot of energy to move it through water quickly. But, if it makes the water really rough, you are going to have to push it harder to get it through. So if you can figure out how much an object disrupts a fluid’s flow, you can figure out how easy it would be to push through water.

This experiment does just that by slowly pouring rheo-scopic fluid down a ramp and having it pass by objects of different shapes. It is easy to see which shapes cause the most turbulence and which cause the least. Because shapes that cause the least turbulence move through water the easiest, they are the most hydrodynamic.

A quick note or two about this experiment: First, it can be tricky to get the water to flow smoothly, so it is important for the students to pour the water very slowly. If there is anything such as a rough piece of tape in the bottom of the

ramp, it will cause its own turbulence and throw things off. Second, there are several variations of this on the web, the most common of which is to put blocks in a dish and use some sort of spatula type device to “push” the water to make it flow. I have no idea who wrote this or why it is so prevalent, but it just doesn’t work. When the water is “pushed” there are too many eddies created by the move-ment of the side of the spatula for the experiment to be of any use. The PhysicsQuest version of this experiment may seem a little fussy, but it requires all this to make sure the kids can actually see the effect.

SAFETYReview these guidelines closely with students before the activity and outline consequences for failure to follow them! Rheoscopic fluid, while not poisonous, is not tasty and could stain. Make sure students do not drink or splash the rheoscopic fluid.

Corresponding Extension Activitiesn Coanda Effect 1 and 2n Spoon liftn Laminar flow

Bibliography/Suggested Resourcesn http://swimright23.webs.com/streamline.htm (scary math but great pictures) n http://www.physicscentral.com/explore/pictures/turbulence.cfmn http://gizmodo.com/5925135/the-worlds-most-aerodynamic-triathlon-bike-even-has-streamlined-snack-storage (The lack of turbulence in the “airplane wing” shape is also used in high performance bikes. This article is a good explanation of why.)


ACTIVITY 1 - B



Figure 1

Water Pipe

Movement of fluidFlap

Tiny, flat shiny pieces


ACTIVITY 1 - C


S T U D E N T G U I D E

INTROWhy can Olympic swimmers Michael Phelps go faster than Ryan Lochte (most of the time)? Why are the hulls of boats shaped like they are? In this experiment you will use some shiny (and slightly smelly) stuff called “rheoscopic fluid” to see how water flows around different shapes MATERIALSn Pen box topn Pipette filled with rheoscopic fluidn Black construction papern Transparency n Sheet with rectanglesn * Bottle with lid (20oz soda bottle works well)n * Cupn * Adhesive tapen * Thin bookn * Watern * Permanent Markern * Scissors *Not included in the PhysicsQuest Kit

GETTING STARTEDWhen you stick your hand out of a car window, does air rush by it more easily when your hand is verti-cal or horizontal? ____________________________________________________________________ How is the front of a barge different than the front of a speed boat? Which do you think is faster?

_________________________________________

What is an eddy? Turbulence? ______________________________________________________________________________________________________________

Can you think of times you’ve seen water flow smoothly? Roughly? White water? _______________________________________________________________________________________________________________________________________

When Michael Phelps cuts through the water, par-ticularly when he is underwater, what shape does he make his body? _____________________________________________________________________

SETTING UP THE EXPERIMENTTHIS PART CAN BE TRICKY. FOLLOW THE INSTRUCTIONS CAREFULLY

1. Place the transparency film over the sheet of paper with the rectangles and trace them with a permanent marker.

2. Cut out the rectangles from the transparency film. Make sure you note which rectangle is for which shape.

3. When taping them together, it is important that the tape lay very flat.

n Cylinder (Fig. 1): Roll the rectangle into a cylinder about half an inch in diameter. There will be some overlap. Tape the seams shut, both the inside and the out-side, making sure the tape lays very flat.

n Triangle (Fig. 2): 1. Fold the rectangle along the dotted lines, mak-ing very sharp edges.

2. Fold into a triangle, two of the flaps will over-lap.

3. Tape, being careful to flatten the tape.

n Square (Fig. 2):1. Roll the rectangle into a cylinder with the short edges just touching. Be careful not to over-lap.

2. Make creases along the dotted lines.

3. It should naturally form a square.

n Wing (Fig. 4):Pinch together the ends so that the two ends are touching, Tape them together using a loop of tape on the inside. You should now have a teardrop shape.

K E Y Q U E S T I O NWhich shapes are more hydrodynamic?


ACTIVITY 1 - D



SETTING UP THE RAMP1. Cut the black construction paper the same size as the bottom of the box and tape it to the outside of the box. This is so that it is easy to see the rheoscopic fluid as it flows through the box.

2. Cut one of the short ends of the box to make a flap.

3. Tape a cup to the side of a desk. Use lots of tape. It needs to be well stuck on the desk..

4. Put the box on the desk with the flap point-ing into the cup and put the other end on the thin book to elevate it. You should have created a ramp for the fluid to flow down and into the cup. (Fig. 5)

Look at the shapes you created. Which do you think will allow the water to flow past with the least turbulence? If something can pass through water with little turbulence, it is said to be “hy-drodynamic.” Predict which shapes will be the most hydrodynamic and line up the shapes in front of you from what you think will be most hydrodynamic to least hydrodynamic.

ANALYZING YOUR RESULTS1. Fill the free cup with rheoscopic fluid.

2. Very slowly pour the fluid from the cup into the top of the ramp. Draw what you see.

3. Now the cup taped to the table is full. Remove it and tape the empty cup to the table.

4. Place the square in the middle of the ramp (Fig. 2) and again pour the fluid down the ramp. You may need to hold it down with your finger, but be careful not to stick your finger in the mov-ing fluid, this will royally screw up your results. Draw what you see:

5. Repeat with the other shapes, each time draw-ing what you see.

CIRCLE

__________________________________________________________________________________________________________________

TRIANGLE

__________________________________________________________________________________________________________________

WING

__________________________________________________________________________________________________________________


ACTIVITY 1 - E



1. What did it look like as the fluid was flowing without a shape in the way? How was it moving? When some-thing is flowing in a straight line without any turbu-lence, it is called “laminar flow.” ____________________________________________________________________________________________________________________________________________________________________________

2. What happened when it ran into one of the shapes? Did its movement change? ____________________________________________________________________________________________________________________________________________________________________________

3. What shapes created the most turbulence? What shapes created the least?

____________________________________________________________________________________________________________________________________________________________________________

4. Think about what would happen if the shape was moving through the water instead of the water moving by the shape. Which ones do you think would move through the most quickly?

____________________________________________________________________________________________________________________________________________________________________________

5. How do you think the turbulence the shape creates in water affects how fast it might move through water?

____________________________________________________________________________________________________________________________________________________________________________

6. What does it mean to be “hydrodynamic”?

____________________________________________________________________________________________________________________________________________________________________________

7. Why do you think Michael Phelps “streamlines” un-derwater to get ahead of the competition?

____________________________________________________________________________________________________________________________________________________________________________

Rank the shapes in order from most hydrodynamic to least hydrodynamic.

1.______

2.______

3.______

4.______

USe YOUR RESULTS TO HELP SPECTRA FIND THE CAFETERIAWhat was your ranking of most hydrodynamic to least hydrodynamic

1. Wing, circle, triangle, square (The gang should go straight.)

2. Square, circle, triangle, wing (The gang should turn left.)

3. Circle, square, wing, triangle (The gang should turn right.)

WIN

G


ACTIVITY 1 - F



Figure 1 Figure 4

Figure 5

Figure 2 Figure 3

Shape templates

CY

LIN

DE

R

SQ

UA

RE

TR

IAN

GLE

NOTE: Images not to scale

Movement of fluid

Tiny, flat shiny pieces

Water

Alright CRYBABIES, I’m going to the boardwalk to have SOME fun. You CAN join me if you WISH, but don’t act like YOU know me,I DO HAVE AN IMAGE TO UPHOLD.

WeLL, i don’t know

about you, “Hobbit”.

but “I” was going

plenty fast.

A few minutes later, the adventurous girls explore the city’s popular beaches and Boardwalk District.

I’m NOT A CRyBABY!BUT THE BOARWALK SOUNDS

better than sitting AROUND here. something isn’t right and maybe SOME FRESH AIR wiLL help us FIGURE IT OUT.

TIFFANY, WAIT FOR US.

RUBY, I WORKED reaLLy hard to swim. but AFTER LooKING AT THoSE TIMES, IT looks

like I was going pretty slow.

I don’t know how to describe WHAT

HAPPENED. but it seemed like I was swimming

upstream AGAINST

THE CURRENT.

LUCy, Don’t woRRy

too much,

everyone

was slow.

By Amy Flatten.com

STOP POINTING THAT CAMERA PHONE THIS WAY! I’M NOT IN THE MooD TO See MY FACE UPLOADED

TO INSTAGRAM.

Lucy and Ruby can’t believe their eyes. It’s their swim coach and it looks like he’s controlling the water’s movement. Ruby’s “investiga-tive blogger” instincts take over as she continues snapping photos with her camera phone.

HEY LUCY, LooK OVER THERE.

is that who I think it is And what’s

going on with THOSE waves? That’s JUST not right.

Oh, C’MON! STOPPING BEING SILLY! I’LL make sure you look good.

Don’t you trust my skiLLs?

The sunset is beautiful. I love being out here and seeing these waves,

The lighting is perfect.NOW, JUST SMILE.

I’m NOT A CRyBABY!

BUT THE BOARDWALK SOUNDS

beTTer than siTTing AROUND here.

something isn’t right and maybe

SOME FRESH AIR wiLL

help us FIGURE IT OUT.

TIFFANY, WAIT FOR US.

STOP POINTING THAT CAMERA PHONE THIS WAY! I’M NOT IN THE MooD TO See MY FACE UPLOADED

TO INSTAGRAM.

Lucy and Ruby can’t believe their eyes. It’s their swim coach and it looks like he’s controlling the water’s movement. Ruby’s “investiga-tive blogger” instincts take over as she continues snapping photos with her camera phone.

HEY LUCY, LooK OVER THERE.

is that who I think it is And what’s

going on with THOSE waves? That’s JUST not right.

Oh, C’MON! STOPPING BEING SILLY! I’LL make sure you look good.

Don’t you trust my skiLLs?

The sunset is beautiful. I love being out here and seeing these waves,

The lighting is perfect.NOW, JUST SMILE.

Oh, C’MON! STOP BEING SILLY! I’LL make sure

you look good. Don’t you trust

my skiLLs?


ACTIVITY 2 - A

ACTIVITY 2: Shaken, not Stirred.


INTROIf you’ve ever gotten a can of mixed nuts, you may have noticed that the Brazil nuts most often end up at the top. It’s not the way they are packed that makes this happen; it’s actually physics. More specifically, it’s an effect that scientists, not without a love of snack food, have named “The Brazil Nut Effect.” You’d think that when things are shaken together, they’d mix but often they separate instead. In this experiment we’ll see what makes shaken things separate and how. This experiment is easy to do, doesn’t require a lot of big, fancy physics words, but it is surprising and awesome.

KEy TERMSDensity: The amount of mass per volume. Metal is more dense than plastic.

Granular material: Any group of grains. Gumballs and sand are examples of granular materials.

Convection: Any movement of a group of molecules in a fluid. The most common example is convection caused by heating.

Granular convection: Motion of grains (as opposed to molecules) due to shaking. It is very similar to liquid convection.

MATERIALSn Clear plastic container with lidn Plastic (yellow or green) spheresn Metal spheresn Wooden spheresn * Adhesive tapen *Cup * Not included in the PhysicsQuest Kit

BEFORE THE ACTIVITY, STUDENT SHOULD KNOWn Metal is more dense than plastic.n Wood and plastic have similar densities. n The definition of convection

AFTER THE ACTIVITY STUDENTS SHOULD BE ABLE TOn Say what happens when particles of different sizes are shaken together

n Say what happens when particles that are the same size but different masses are shaken together

n Explain what is meant by the “Brazil Nut Effect.”

THE SCIENCE BEHIND SHAKEN, NOT STIrrEDThough they no longer put prizes in cereal boxes, I’m guessing that as a kid, most of us had them. And most of us also had the experience of either having to wait till the box was almost empty to get the prize or having to open the box from the bottom. And, if you’ve ever had the experience of being late for a party and grab-bing a can of mixed nuts as your food contribution, you know that the Brazil nuts always end up on top. You can blame physics for both. Physics apologizes for the ce-real box toy thing. But why is this happening? Usually we shake things to mix them, such as salad dressing or a good martini. However, systems made of “grains,” such as cans of nuts and boxes of Cap’n Crunch Berries ce-real, behave differently than either solids or liquid and there is a whole branch of physics devoted to studying them called granular materials. It’s an extremely im-portant field of physics, particularly for manufacturing things like gumballs and pharmaceuticals in pill form. If candy needs to be mixed or separated, it’s important to know the physics involved. Grains are a weird type of system, made up of solids you can see but often behaving like a liquid. In fact, a lot of terms used for liquids, such as convection and flow are also used for granular materials.

Think about what makes a liquid a liquid. The mole-cules can move around easily, they aren’t in any par-ticular order and there is a lot of space between them. When a group of grains in a container is shaken, it can be thought of as a “liquid” because it has the same prop-erties. The grains can move around easily, they aren’t in any particular order and there is a lot of space be-tween them. Shake them even harder and they become a granular gas. And just like liquids and gases, they un-dergo convection. Granular convection is not driven by heat as it usually is in liquids and gases. Rather, it is driven by vibration and friction between the grains and the walls of their containers. This activity has two ex-periments that look at how the grain’s density and size affect how they move around in these granular liquids and gases (Fig. 1).

K E Y Q U E S T I O NHow do density and size affect how spheres mix when they are shaken?


ACTIVITY 2 - B



The first experiment involves a whole lot of tiny plastic spheres and about 3 larger wooden spheres. When the container is shaken, the energy of the shak-ing causes the grains to rise, but the grains next to the container wall can’t jump up as far because of the friction with the walls.

As the spheres keep moving up the middle they slowly push down the spheres on the side and a con-vection current is set up. The larger wooden spheres that started out on the bottom get pushed up with this convection current too. Unlike the rest of the spheres, though, they get stuck at the top. When the container is shaken, it adds a lot of space between the grains, but the spaces are still smaller than the size of the wooden spheres. Once they are at the top, they can’t fit back into the granular convection current. The get stuck there as all the smaller spheres fill in below them. This is called the Brazil Nut Effect (Fig. 2).

The second experiment involves spheres of the same size but different densities. In this experiment the con-tainer is shaken at an angle instead of up and down. Because it is at an angle the convection currents are set up as before. When the container is shaken the grains have a lot of space between them and still have gravity pulling them towards the floor. They can be seen as a “granular liquid.” In fact, if the container was a lot bigger and you shook them really hard, they might actually even be a granular gas. The grains do

exactly what we know all liquids do, they separate out based on density. The heavier metal spheres go to the bottom and the lighter plastic spheres move to the top. It is neat to try this experiment while holding the container straight up and down. You can watch the metal spheres in the sea of plastic and see the con-vection currents being set up (Fig. 3). Grains can be so interesting because they just don’t quite fit in any of the standard categories of states of matter, but are everywhere. The physics of grains can save you from an avalanche, separate gummy bears from gumballs and tell you how to build a salt storage silo. These are just two fun granular experiments but there are many, many more you can find and try out. Personally, I think this is one of the neatest branches of physics.

SAFETYReview these guidelines closely with students before the activity and outline consequences for failure to follow them! Do not ingest the spheres. They are a choking hazard. Though this is called the Brazil Nut Experiment, nothing is actually edible. Always closely monitor students as they experiment with the spheres.

Corresponding Extension Activitiesn Shock Absorbent Sandn Angle of Reposen Density Ball Sorting

Bibliography/Suggested Resources

n http://io9.com/5786442/the-brazil-nut-effect-why-the-biggest-nuts-rise-to-the-topn http://www.null-hypothesis.co.uk/article/1303n http://physicsworld.com/cws/article/news/2001/apr/11/cracking-the-brazil-nut-problemn http://www.wildsnow.com/520/the-brazil-nut-effect-how-to-survive-an-avalanche/

Direction to shake

Direction to shake

Figure 1 Figure 2 Figure 3


ACTIVITY 2 - C



INTROIf you’ve ever gotten a can of mixed nuts, you may have noticed that the Brazil nuts end up at the top most of-ten. It’s not the way they are packed that makes this happen, it’s actually physics. More specifically it’s an effect that scientists, not without a love of snack food, have named, “The Brazil Nut Effect.” You’d think that when things are shaken together, they’d mix but often they separate instead. In this experiment we’ll see what makes shaken things separate and how. This experiment is easy to do, doesn’t require a lot of big, fancy physics words, but is surprising and awesome.

KEy TERMSDensity: The amount of mass per volume. Metal is more dense than plastic.

Granular material: Any group of grains. Gumballs and sand are examples of granular materials.

Convection: Any movement of a group of molecules in a fluid. The most common example is convection caused by heating.

Granular convection: Motion of grains (as opposed to molecules) due to shaking. It is very similar to liquid convection.

MATERIALSn Clear plastic container with lidn Plastic (yellow or green) spheresn Metal spheresn Wooden spheresn * Adhesive Tapen *Cup * Not included in the PhysicsQuest Kit

GETTING STARTED1. What do you think happens when you have a bunch of spheres, such as gumballs or beads in a container and shake it. Do they mix? Do they move around in any particular way? ___________________________________________________________________________________________________

2. If you could see the molecules of gases and liquids, what do you think they would look like? Would they be spread out or close together? Would they be moving? ___________________________________________________________________________________________________________________________

3. If you had liquids of two different densities in the same cup, what would happen? ________________________________________________________________________________________________________________________

SETTING UP THE EXPERIMENTYou will be doing two separate experiments. In the first one, you will see what happens when spheres of two different sizes but the same density are mixed together and then shaken. In the second you will investigate what happens when you do the same thing with spheres of the same size but different densities.

n Experiment 1: 1. Put the wooden spheres in the bottom of the con-tainer and then pour the plastic spheres on top.

2. Put the lid on and seal with a strip of tape.

3. What do you think will happen to the wooden spheres when you shake the container? ___________________________________________________

4. Shake the container up and down roughly 20 times. Make sure the bottom is horizontal and that you are shaking it directly up and down. Watch what happens to the wooden spheres as you shake the container (Fig. 1). Are they moving? How? Record the number of wooden spheres on the top and bottom of the con-tainer. Top_______ Bottom______

5. Turn the container over so that the lid is now fac-ing down and the bottom is now the top (good thing you taped the lid on!). Repeat the experiment and again write down the number of spheres on the top and bottom (the lid side is now the bottom). Top_______ Bottom______

6. Do this a few more times and average your results.

7. Top Average________ Bottom Average_______

K E Y Q U E S T I O NHow do density and size affect how spheres mix when they are shaken?

Direction to shake

Figure 1


ACTIVITY 2 - D



n Experiment 2: 1. Remove the wooden spheres from the container and dump the plastic spheres into the cup.

2. Add the metal spheres to the cup and use your hand to mix them around till they are well mixed. Don’t shake! Use your hand to mix them.

3. Pour the mixture of spheres into the con-tainer and again tape the lid on (Fig. 2).

4. Hold the container at a slight angle and shake vig-orously for several seconds. What is happening to the metal spheres as you are shaking? Are they moving? How? ________________________________________________________________________________________________________________________________________________________________________

5. Count the number of metal spheres you see at the bottom and the number at the top. Top_______ Bottom________

5. Turn the container over and repeat the experiment. Top____ Bottom____

6. Repeat the experiment several more times and aver-age your results

Top Average____ Bottom Average____

ANALYZING YOUR RESULTSn Experiment 1:1. How did the wooden spheres behave when the container was shaken? Was this what you thought would happen? __________________________________________________________________________________________________________________________________________

2. Did they move up the middle or up the sides? How did the plastic spheres move?__________________________________________________________________________________________________________________________________________

3. Do you think the spheres are more like the molecules in a solid, liquid or gas when they are shaken?_____________________________________

_____________________________________________________________________________________________________

n Experiment 2: 1. How did wooden spheres behave when the container was shaken? Was this what you thought would happen? __________________________________________________________________________________________________________________________________________

Did they move up the middle or up the sides? How did the plastic spheres move? __________________________________________________________________________________________________________________________________________

Do you think the spheres are more like the molecules in a solid, liquid or gas when they are shaken?

__________________________________________________________________________________________________________________________________________

What happens when you have a liquid with two different densities? How does this compare to the shaken spheres?

__________________________________________________________________________________________________________________________________________

Using your results to help Spectra and HER FRIENDS find the kitchen

What happens when the container is shaken?

n The wooden spheres and the metal spheres rise to the top _____________________ (The gang should go straight.)

n The wooden spheres sink and the metal spheres rise ________________________ (The gang should go left.)

n The metal spheres sink and the wooden spheres rise ________________________ (The gang should go right.)

Direction to shake

Figure 2

Look at the way it flows, twists

and catches the moonlight.It’s BEAUTIFUL!

GET BACK! HE’S LooKING THIS WAY. I don’t want him to see us. Let’s get out

of here.

unless there are reaLLy HYPER

dolphins out there!It reaLLy looks

like COACH IS making

the water dance

I have no idea HOW I’M MAKING THIS HAPPEN, BUT WOW, THIS IS AMAZING! Water can do whatever I teLL it to DO. Not only is THIS fun, it’s a great way to train the SWIM team. We’re definitely going to beat THAT THOMAS A. Edison Middle School AT THE MeeT this year!

They head down to the beach, and try not to be seen by Coach Henri Toueaux.

WHOA! that’s definitelynot normal. THE Waves ARE crashING

onto the beach not away from it.But how can COACH be doing that?

it’s against thelaws of physics!

LUCY, you turn into a laser. I don’t think you’RE the one to say

superpowers aren’t possible.

Point taken! JUST KeeP TAKING

THE PHOTOS.

????

WE have to WIN!

They can’t win again, I wiLL

be the laughing stock of

Sequoia University

QUIckie Coaching School.

I always come in

second, but not this year.

Not with this power!

The championship WILL BE mine!

Mine I say!

They head down to the beach, and try not to be seen by coach Henri Toueaux.

See LUCY, you look

great in that pic.

THAT’s Definitely

a profile

PHOTO.

Ruby, PLEASE focus!

We’re trying to see if

you got a picture of

Coach moving water

and hopefuLLy WE can

figure out how

HE DOES IT.

If we have

a picture, we

can prove it

if we need to.

WELCOME BACK! how was the

training IN CALI? you HARDLY SENT

ME ANY TEXT MEssAGES.

I was woRRied.

KAS, It was brutal! I’VE never swum so hard

in my life. It FELT LIKE the water was fighting

AGAINST me WITH EACH LAP.

Let’s meet up after school; bring Gordy.

Ruby AND I WILLFILL you in.

Back at Nikola Tesla Junior High School

The next day, the swim team flies back home. Still confused at what they saw last night, neither Lucy nor Ruby mentions it to the Coach or the other swimmers.

Later that day, the friends meet up at the Pizza Joint. They tell the guys about the Coach’s alleged powers.

it’s bluRRy, BUTLooK AT THIs one,

I don’t know if that’s water going the

wrong way or just a smudge.

WeLL, it’s not convincing at aLL. Maybe it was nothing. And even if it was something,

maybe it doesn’t matter, it’s not like he was

hurting anyone.

In the morning, the swim team flies back home. Still confused at what they saw last night, Lucy nor Ruby mention it to the coach or the other swimmers.

Later that day, the friends meet up at the Pizza Joint. They tell the guys about the coach’s alleged powers.

Lucy, You aren’t

being very

helpful. It’s not

like we know he’s

going to do

anything.

So far there

have been

surprisingly

few threats

to take over

the world or kiLL

us aLL. He just

splashes WATER

AROUND. what exactly

do you want us to do?

Ok, OK, calm down. we HAD PLANNED TO BE THERE ANYWAY. NOW WE’LL BE on the lookout FOR ANYTHING STRANGE.

Super powers are never

nothing. Maybe that’s why

we had to work twice as

hard at SWIM practice.

If I were a coach and I

wanted my team to BE FIT

AND work harder, I’d USE

ANYTHING NECEssARY WITH

THE WATER TO make them

work harder!

HIS “POWER” WAS hurting

people. The whole team

is on the verge of

being injured OR Worst!

THANKS GUYS!

I DON’T KNOW! I just know that a coach who has superpowers and an unswerving desire to win is never a good

combination.

He’s losing his mind and I’m woRRied we wiLL aLL be in the way. Just promise me you wiLL be at the swim meet this Friday and keep

an eye out for anything odd.

Friday’s State Championship Swim Meet features the Nikola Tesla Junior High School Chargers vs. the Thomas A. Edison Middle School Wizards. The schools have a long running and competitive rivalry.

*To find out why Nikola Tesla believes Thomas Edison owes him $50,000; see PhysicsQuest 2008 Nikola Tesla and the Electric Fair

STOP MAKING

EXCUSES, LUCY.

GET READY FOR

THE NEXT RACE!

AND JUST TO MAKE CERTAIN OF

VICTORY, I WILL BE TO USING MY

“SPECIAL” GIFT ...

TO WIN IT ALL!

Just once I would like a fair relay race. Last year I was

almost boiled alive. this year the water is going the wrong way! Why does this place

make it so hard!

A crazed Coach H20 uses his power of water manipulation to attack the other team. He doesn’t stop at the Edison Middle School swimmers. He also goes after the fans. No one is excluded from the chaos.

CHARGERS! I’M NOT HAPPY!

LooK AT THAT SCORE.WHY ARE WE TIED WITH

THOSE WIZARDS!

THE SCORE IS TIED BECAUSE OF YOUR WEAK RELAY

PERFORMANCE!

COACH, YOU WORKED US SO HARD AT

PRACTICE THAT ALL OUR SHOULDERS AND LEGS ARE

ACHING! I CAN BARELY SWIM!

A crazed coach H20 uses his power of water manipulation to attack the other team. He doesn’t stop at the Edison Middle School swimmers. He also goes after the Edison and Tesla Middle School fans. No one is excluded from the chaos.


ACTIVITY 3 - A

ACTIVITY 3: Vortex CannonT E A C H E R G U I D E

INTROWe’ve all watched The Hobbit, Bilbo Baggins blow smoke rings or watched whirlpools in the tub. Even dol-phins like to play with bubble rings. Why does the air al-ways end up in a circle? What happens if you try to force the air into other shapes such as a square or a triangle? In this experiment we will build a “vortex cannon” and see what happens when air is forced out through a rectangu-lar or triangular hole instead of a circular one. In Activity 2 you looked at how water flowed around objects, now you are going to look at how it flows through holes. KEy TERMSVortex: Fluid that is flowing in swirls instead of a straight line. Whirlpools are a type of vortex.

Torus: A shape like a donut or a bagel

MATERIALSn Rubber bandn Plastic bagn Tissue papern * Paper cupn * Adhesive tapen * Scissorsn * Index cards *Not included in the PhysicsQuest Kit

BEFORE THE ACTIVITY, STUDENTS SHOULD KNOWn The definition of a vortex and a torus

AFTER THE ACTIVITY, STUDENTS SHOULD BE ABLE TOn Say which shape allows the air from the cannon to travel the farthest.

n Describe why a vortex travels the farthest.

n Explain why the air pushed through a triangle and a square do not create a vortex

THE SCIENCE BEHIND THE VORTEX CANNONWe see vortices everywhere, from flying cows in “Twist-er” to watching the tub drain. One thing that is always the same, they move in a circular pattern. You’ll never see a square tornado or a triangular whirlpool. But why is that? Is it just that they always start as circles so they stay that way? What would happen if a tornado started off in the shape of a triangle, would it stay in that shape? It turns out the answer is “no” for the same reason you can’t make a square bubble.

This experiment involves building a “vortex cannon” which is just a fancy way of saying something that push-es a puff of air through a hole to create a traveling ring of air. You’ve probably played with that evil toy, the “air-zooka” which does a great job smacking people in the face with a huge, strong blast of air. How is it able to move air like that? There are two components to making a good vortex cannon, being able to push the air with lots of force and shaping the hole through which the air exits correctly. In the case of our homemade cannon, the air is pushed using a rubber band and a plastic bag. The rubber band is stretched when the bag is pulled back and air is pulled into the cup. When you let go of the bag, the rub-ber band pulls it in quickly and air is rapidly pushed out of the front of the cannon. If the mouth of the cannon is in the shape of a circle, a vortex is created. A vortex is any type of twist or swirl in a fluid. The neat thing is that vortices are extremely stable, meaning its difficult to change their motion. So if you manage to create a vortex of air, it’s going to take a lot to get it to change. A vortex is created by the cannon because as the puff of air passes through the hole the outside gets a little caught on the edge and gets slowed down. The middle part of the puff has no such problem and ends up travel-ing faster. Because of the speed difference, the air in the middle starts swirling out towards the outside as the air from the outside starts swirling back in. What’s created is a donut of air that is swirling from the inside out. The air has no particularly reason to stop doing what it’s doing. It is extremely stable and travels easily through the sur-rounding air without being slowed down much. It also won’t easily break apart. This is why tornados and bath-tub swirls don’t break up that easily. (Fig. 1) What would happen if the front of the cannon had a shape other than a circle? Because of the edges of any shape other than a circle, the air leaving the cannon isn’t forced into a vortex. Which means its not very stable and won’t travel as far. Some shapes may be close enough to a circle to create a weak vortex, but it won’t be nearly as good as a circular opening. (Fig. 2) Because there is no good way short of a fog machine to see a vortex, this experiment uses tissue paper flags to see

K E Y Q U E S T I O NWhich vortex cannon shape will allow air to travel the farthest?


ACTIVITY 3 - AP H Y S I C S Q U E S T : S P E C T R A - T U R B U L E N T T I M E S ( I S S U E # 5 )

ACTIVITY 3 - B

ACTIVITY 3: Vortex CannonT E A C H E R G U I D E

how far the puffs of air from different cannon shapes goes. It is important to make the circular opening as close to a circle as possible to get the best effect.

If you would like a video explaining how to make the paper cup vortex cannon, visit this site: http://construction-toys.wonderhowto.com/how-to/make-air-vortex-cannon-272086/ The materials are different, but the principle is the same.

SAFETYn Review these guidelines closely with students before the activity and outline consequences for failure to follow them! Always be careful with scissors and rubber bands. Stretched rub-ber bands can hurt if they are let go too quickly.Be cautious when cutting out shapes as it is sometimes difficult to cut a shape out of the center of a card. With younger students this part should be done by an adult.

Corresponding Extension Activitiesn Air Flown Siphoningn Cold Lava Lamp

Bibliography/Suggested Resourcesn http://thesciencepresenter.wordpress.com/2011/01/16/wheres-the-science-airzookas/n http://www.physicscentral.com/experiment/physicsathome/cannon.cfmn http://amasci.com/wing/smring.html

Figure 1

Figure 2


ACTIVITY 3 - C

ACTIVITY 3: Vortex CannonS T U D E N T G U I D E

INTROWe’ve all watched The Hobbit, Bilbo Baggins blow smoke rings or watched whirlpools in the tub. Even dolphins like to play with bubble rings. Why does the air always end up in a circle? What happens if you try to force the air into other shapes such as a square or a triangle? In this experiment we will build a “vortex cannon” and see what happens when air is forced out through a rectangular or triangular hole instead of a circular one. In Activity 2 you looked at how water flowed around objects, now you are going to look at how it flows through holes. KEy TERMSVortex: Fluid that is flowing in swirls instead of a straight line. Whirlpools are a type of vortex.

Torus: A shape like a donut or a bagel

MATERIALSn Rubber bandn Plastic bagn Tissue papern * Paper cupn * Adhesive tapen * Scissorsn * Index cards*Not included in the PhysicsQuest Kit

GETTING STARTEDn Think about whirlpools. What shape are they in? n Now think about smoke rings, what shape are they in? n Why do you think they are in those shapes and not oth-ers? n Do you think their shape affects how they move?

SETTING UP THE EXPERIMENTThis can be a bit tricky. If you are having problems, ask your teacher for help, he or she can show you a video of how it’s done (Fig. 1).

Making the cannon1. Cut the bottom out of the paper cup as cleanly as pos-sible.

2. Cut the bag so that it is one sheet of plastic.

3. Lay the cup top down on the piece of plastic and trace it.

4. Cut the plastic into a circle that has a radius 3-inch bigger than the top of the cup.

5. Cut two small slits about half an inch apart in the cen-ter of the plastic circle.

6. Cut the rubber band so it is a rubber strip instead of a rubber band.

7. Thread the two ends of the rubber band through the two slits and tape the plastic to the rubber band. Use plenty of tape.

8. Again lay the cup top down over the center of the plas-tic, but this time thread the rubber bands up through the bottom of the cup.

9. Pull rubber bands up and out of the bottom of the cup. As you do this the disk of plastic will be pulled up and into the cup. Keep pulling the rubber bands until the plas-tic has been pulled half of the way into the cup. Fold the rubber bands around down to the outside of the cup and tape. Use lots of tape.

10. Take the plastic disk and fold the outside edges up and around the outside of the cup. Tape very tightly. Use lots of tape and make sure it is all sealed very well.

You should now have plastic at one end and an open-ing at the other. When you pull the plastic back you should be able to let it go and have air forced out of the hole.

Making the cards and flags1. Take three index cards and draw a circle on one, square on another and triangle on the third

2. Carefully cut out the shapes.

3. Take the tissue paper and cut into one inch squares. These will be used as “flags.” (Fig. 2)

4. Tape the flags to a long bookshelf or a series of desks so that they are one inch apart. They should have one free side just like a flag so that if air rushes by it can flap in the wind. This is how you are going to test to see how far your air cannon can shoot.

K E Y Q U E S T I O NWhich vortex cannon shape will allow air to travel the farthest?


ACTIVITY 3 - CP H Y S I C S Q U E S T : S P E C T R A - T U R B U L E N T T I M E S ( I S S U E # 5 )

ACTIVITY 3 - D

ACTIVITY 3: Vortex CannonS T U D E N T G U I D E

EXPERIMENT1. Put a line of tape on the floor 1 meter away from the first flag.

2. Tape the index card with the triangle and tape it to the front of the cannon so that when “fired” the air will be forced through the trian-gular hole.

3. Stand on the tape line and “fire” the air can-non so that the puff of air hits the edge of the flags. It may take several tries to aim correctly. Once it is lined up, shoot the cannon at the flags 10 times and count how many flags wiggle each time. _______________________________________________________________________________________________________________

4. Average these numbers together to get the average number of flags that wiggled.

5. Repeat these steps with the square and circle.

RECORD THE AVERAGE HERE

Triangle ______________________________

Square _______________________________

Circle ________________________________

ANALYZING YOUR RESULTS1. Which shape allowed the air to travel the farthest? __________________________________________________________________________

2. What is one big difference between the circle and the other two shapes? __________________________________________________________________________

3. Rank the shapes in order from most corners to least corners. How does this compare to the ranking of distance traveled? _______________________________________________________________________________________________________________

4. What shape are smoke rings and how does the shape that allowed the air to travel the far-thest compare?

_______________________________________________________________________________________________________________

5. How far do you think air would travel if forced through a hexagon? How about an oc-tagon? _______________________________________________________________________________________________________________

6. Using your results to help Spectra and the gang find the kitchen.

_______________________________________________________________________________________________________________

Which shape allowed the air to go the far-thest?

1.Triangle (The gang should go straight)

2. Square (The gang should go left)

3. Circle (The gang should go right)

Figure 2

Figure 1

PlasticTapeRubber band

Slits

Tissue paper

BUT GUYS, Isn’t there water in ketchup?

I have an idea! c’Mon

Let’s HEAD TO THE

CAFETERIA.

The quartet of young heroes burst into the school’s kitchen.

OK! BUT I THINK IT’s

TIME FOR SPECTRA TO

MAKE AN APPERANCE!

We’ve got to stop COACH! I’M NOT FAN OF Edison Middle School EITHER, but he’s REALLY

hurtING PEOPLE!

He’s too powerful and I don’t know what my laser powers can

DO AGAINST HIM!

YOU’RE RIGHT RUBY,REMEMBER WHAT WE

learnED IN PHYSICS CLASS. We’RE just going

to make it easier for him, not trap him.

when you move ketchup, it BECOMES easier to move.

Lucy, help ME with this corn starch!

Over there, get the ketchup,

it’s thick!

I Just felt like I should be READY.we are saving the school, aren’t we?

How is a laser suPPosed to help you move stuFF?

DUMP ITNOW!

HE HA!DE HA!

HA DA!

you can’t trap me!

FooLISHCHILDREN,

While the Coach is distracted by Spectra, Gordy, Ruby and Kas take the tops off the corn starch and ketchup.

The Coach focuses his attention on Spectra and he loses control of the pool’s water. He stumbles and falls back into the pool.

Spectra yells, “Gordy, your plan is working.”

The group takes all the ketchup and corn starch they can carry to the pool.

Coach attempts to continue his outburst at the aquatic center. He tries to create a vortex and only succeeds in mixing the corn starch, ketchup and water even more. The more he tries to move the water, the thicker the mixture becomes.

A LASER CAN’T,

but you CAN! aren’t

you a swimmer with

big arms? Forget

the laser stuFF

and HELP! BTW, why

are you in YOUR

spectra outfit?

Everyone dumps the corn starch and ketchup in the water. They make a mess!

Hey Coach, over here!

If you want to attack

someone, attack me!

I’m the one that lost

the big relay.

It’s my fault.

we lost!

Lucy?!!

I Just felt like I should be READY.we are saving the school, aren’t we?

How is a laser suPPosed to help you move stuFF?

DUMP ITNOW!

HE HA!DE HA!

HA DA!

you can’t trap me!

FooLISHCHILDREN,

While the Coach is distracted by Spectra, Gordy, Ruby and Kas take the tops off the corn starch and ketchup.

The Coach focuses his attention on Spectra and he loses control of the pool’s water. He stumbles and falls back into the pool.

Spectra yells, “Gordy, your plan is working.”

The group takes all the ketchup and corn starch they can carry to the pool.

Coach attempts to continue his outburst at the aquatic center. He tries to create a vortex and only succeeds in mixing the corn starch, ketchup and water even more. The more he tries to move the water, the thicker the mixture becomes.

A LASER CAN’T,

but you CAN! aren’t

you a swimmer with

big arms? Forget

the laser stuFF

and HELP! BTW, why

are you in YOUR

spectra outfit?

Everyone dumps the corn starch and ketchup in the water. They make a mess!

Hey Coach, over here!

If you want to attack

someone, attack me!

I’m the one that lost

the big relay.

It’s my fault.

we lost!

Lucy?!!

While the coach is distracted by Spectra, Gordy, Ruby and Kas take the tops off the corn starch.

The coach focuses his attention on Spectra and he loses control of the pool’s water. He stumbles and falls back into the pool.

Spectra yells, “Guys, the plan is working.”

The group takes all the corn starch they can carry to the pool.

Coach attempts to continue his outburst at the aquatic center. He tries to create a vortex and only succeeds in mixing the corn starch and water even more. The more he tries to move the water, the thicker the mixture becomes.

Everyone dumps the corn starch into the water. They make a mess!


ACTIVITY 4 - A

ACTIVITY 4: Do You Want Ketchup with Your Physics? T E A C H E R G U I D E

INTRO“Viscosity” is a term that describes how easy it is for a fluid to flow. For most types of fluids, the viscosity doesn’t change. These fluids are called “Newtonian” fluids. But there are certain types of fluids that change viscosity if they are moving. In this experiment you will play with two “Non-Newtonian” fluids and learn why tapping a ketchup bottle will make your fries tast-ier more quickly.

KEy TERMSViscosity: A measure of how easily a fluid flows. The higher the viscosity, the more difficult it is for the fluid to flow.

Newtonian Fluid: A fluid that has the same viscosity no matter how fast it is flowing. Most fluids you have ever seen are “Newtonian Fluids.”

Non-Newtonian Fluid: A fluid whose viscosity de-pends on how fast it is flowing.

Shear-Thinning Fluid: A fluid whose viscosity de-creases the faster it flows. Stirring or shaking will de-crease the viscosity

Shear-Thickening Fluid: A fluid whose viscosity increases the faster it flows. Stirring or shaking will increase the viscosity

MATERIALSn Tart pastry pans (4)n “Sand” made of small green beadsn Ketchupn * Watern * Adhesive tapen * Scissors * Not included in the PhysicsQuest Kit

NOTE: It’s possible to let the oobleck made with the glass beads dry out so that the beads can be reused.

BEFORE THE ACTIVITY, STUDENTS SHOULD KNOWn Most fluids flow in the same way no matter if they are flowing fast or slow.

n Oobleck is a material usually made of cornstarch and water. It can also be made of glass spheres as it is in this experiment.

n Some fluids flow more easily than others.

AFTER THE ACTIVITY, STUDENTS SHOULD BE ABLE TOn Define “viscosity”

n Explain that ketchup and oobleck flow differently when they are stirred.

n Be able to determine if a fluid is “shear-thinning” or “shear-thickening”

n Explain why “tapping the 57” works to get ketchup out of a bottle.

THE SCIENCE BEHIND

DO YOU WANT KETCHUP WITH YOUR PHYSICSThere are tons of different types of fluids, from cof-fee (yum!) to things like molasses. A fluid is anything that flows. I’m now required by high school physics teachers around the country to point out that gases are also fluids. They also can flow. We’re used to fluids such as water that flow in the same way no matter how fast they are moving. Since stirring those can be about as interesting as watching paint dry, this experiment is going to show fluids that don’t do what you’d expect.

When talking about fluids one of the most important properties to look at their its viscosity. The best con-ceptual way to think of viscosity is that it is a measure of how much a fluid resists flowing. Water has a lower viscosity than honey. There are special types of fluids called “superfluids” that have zero viscosity at very low temperatures, as low as -459 degrees Fahrenheit. They can move almost forever without stopping.

On the opposite end of the scale are fluids that have such high viscosity that they actually look like solids.

One famous example is pitch. There is an experiment that watches pitch drip from a funnel and in 80 years it has only dripped eight times. It is about to drip for the ninth time and if you are interested in watching, a live webcam feed can be seen here: http://smp.uq.edu.au/content/pitch-drop-experiment In the 80 years of the experiment, no one has ever seen it drip nor caught the drip on camera. Here’s hoping the ninth time’s the charm.

K E Y Q U E S T I O NHow does the flow of ketchup and oobleck change when they are stirred?


ACTIVITY 4 - AP H Y S I C S Q U E S T : S P E C T R A - T U R B U L E N T T I M E S ( I S S U E # 5 )

ACTIVITY 4 - B

ACTIVITY 4: Do You Want Ketchup with Your Physics? T E A C H E R G U I D E

For almost all fluids the viscosity doesn’t depend on how fast a fluid is flowing. Water for example has the same viscosity if it is moving slowly or quick-ly. Think of stirring hot milk on a stove, if you stir faster it doesn’t feel any different than if you stirred slowly. These types of fluids are called “Newtonian” fluids. They are by far the most common and behave as one thinks a fluid should behave. However, the ones we are going to play with in this experiment are called “Non-Newtonian” fluids. This means that if they are pushed or stirred, their viscosity changes. Sometimes they have a lower viscosity when they are stirred and sometimes the viscosity become greater. Stirring can also be called applying a shear force. So, if something stiffens when stirred its called “shear thickening” and if it gets less viscous it is called “shear thinning.”

The most common Non-Newtonian fluid is corn starch and water, called oobleck. It is often thought that the interesting properties of oobleck are caused because of a chemical interaction between the corn starch molecules and the water. This is not the case. It is shear thickening because of the shape of the corn starch molecules. The molecules are surpris-ingly spherical. I’m guessing that there are many people out there who won’t believe this right off the bat. The PhysicsQuest kit has tiny glass beads that are used to make the oobleck instead of the tradi-tional corn starch as a way to convince the doubt-ers that it is in fact the shape and not the chemicals. But why do these spheres cause the oobleck to “lock up” when it’s stirred quickly? When you try to move a spoon or your finger through oobleck, the tiny spheres have a hard time moving around each other and the water molecules quickly enough to flow. It’s as if they jam up against each other like people all trying to squeeze through a door in a mad rush to get Justin Bieber’s autograph. But if it is pushed more slowly there is time for the particles to roll and slide

over one another and it can move easily. Like form-ing an orderly line to exit a door. (Fig. 1)

Ketchup is not often thought of as Non-Newtonian, it is usually just thought of as hard to get out of the bottle. I wish I could give an simple explanation of why ketchup is a shear-thinning fluid, but I can’t. In fact, people are still actively researching how the ketchup molecules move and why that makes ketchup behave like it does. I think it’s pretty neat that scientists are actually studying the movement of ketchup! Ketchup is really made of ground up toma-to suspended in a sugar-water solution. The current most plausible explanation is that when the ketch-up is sitting still the tomato molecules are moving around randomly but when it is pushed they line up and slide over each other more easily. (Fig. 2)

Scientists are actively doing research on these inter-esting fluids to find out more about why and how they move as they do. In a lot of types of manufac-turing it is critical to know how fluids move to make sure production works smoothly. So have a great time playing and experimenting with some messy, tasty physics.

SAFETYn Review these guidelines closely with students be-fore the activity and outline consequences for failure to follow them! Do not inhale the glass beads. If a large quantity is directly inhaled it can cause lung problems. Be careful to monitor students when us-ing the ketchup packets. If stepped on on rolled over they can cause quite a mess.

Corresponding Extension Activitiesn Moon Blob Geln Comparing the Viscosity of Fluidsn Anti-Bubbles

Bibliography/Suggested Resourcesn http://physicsbuzz.physicscentral.com/2012/04/non-newtonian-barry-white.htmln http://physicsbuzz.physicscentral.com/2012/05/nanotech-and-condiments.htmln http://www.instructables.com/id/Oobleck/n http://arstechnica.com/science/2005/11/1771/

Figure 1Figure 2

Stirring slowly Stirring quickly Ketchup


ACTIVITY 4 - C

ACTIVITY 4: Do You Want Ketchup with Your Physics?


INTROYou’ve probably been in the situation where you’ve tried to dump ketchup on your fries but it just won’t come out of the bottle. You’ve also probably had some-one tell you to “tap the 57” to get the ketchup to flow and its worked. This isn’t some magic little trick, it’s physics and you are going to learn why. If you’ve ever played with “oobleck,” the fun mixture of corn starch and water, you know it does the opposite. When you move it slowly, it flows but if you try and move it fast, it becomes impossible. You’re going to get to learn all about this in this experiment.

KEy TERMSViscosity: A measure of how easily a fluid flows. The higher the viscosity, the more difficult it is for the fluid to flow.

Newtonian Fluid: A fluid that has the same viscosity no matter how fast it is flowing. Most fluids you have ever seen are “Newtonian Fluids.”

Non-Newtonian Fluid: A fluid whose viscosity de-pends on how fast it is flowing.

Shear-Thinning Fluid: A fluid whose viscosity de-creases the faster it flows. Stirring or shaking will de-crease the viscosity

Shear-Thickening Fluid: A fluid whose viscosity in-creases the faster it flows. Stirring or shaking will in-crease the viscosity

MATERIALSn Tart pastry pans (4)n “Sand” made of small green beadsn Plastic spoonn Ketchupn * Watern * Adhesive tapen * Scissors* Not included in the PhysicsQuest Kit

NOTE: It’s possible to let the oobleck made with the glass beads dry out so that the beads can be reused.

GETTING STARTED1. When you hold a bottle of ketchup upside down (not the squeezy kind), what happens? Does it flow?

2. What would happen if you did the same with a bottle of water?

3. What do you think is the difference?

4. If you’ve played with oobleck (a mixture of corn starch and water), what happens when you pour it slowly? What happens when you smack it?

5. If your parents/teachers will let you use the Inter-net, ask them to show you the video of people run-ning across pools of corn starch and water mixtures.

6. The “sand’ you are using to make oobleck is made of tiny glass spheres, not corn starch. Do you think oobleck moves the way it does because of the fact corn starch is also tiny spheres or because there is some chemical interaction between the cornstarch and water?

SETTING Up THE EXPERIMENT

n You will be making two of the tart pans into fun-nels

1. Take two of the tart pans and cut a slit from the outside to the center of the pan.

2. Roll the pans into a cone shape.

3. Cut of the tip of the cone off to make a funnel

n Making the ketchup solution1. Squeeze the contents of the two ketchup packets into a cup.

2. Add 2 spoonfuls of water to make the ketchup slightly less viscous.

3. Stir until the solution is well mixed.

n Making the oobleck1. Place 5 spoonfuls of glass “sand” in a cup.

2. Add 3-4 spoonfuls of water and mix.

3. The mixture should become hard to stir if the spoon is pushed through quickly, but if you move it slowly it should still be moveable. Add more “sand” or water as needed to get the right consistency.

K E Y Q U E S T I O NHow does the flow of ketchup and oobleck change when they are stirred?


ACTIVITY 4 - D

ACTIVITY 4: Do You Want Ketchup with Your Physics? S T U D E N T G U I D E

TIME TO GET MESSY!n Drip Test

If ketchup and oobleck were allowed to drip through a funnel, how do you think the dripping will change when they are stirred? Will it be the same for the ketchup and the oobleck?

1. Hold one of the funnels over a tart pan.

2. Fill the funnel with ketchup. Record what hap-pens. ______________________________________________________________________________________________________________

3. Take the spoon and stir the ketchup in a circle, don’t try and push it through the hole in the fun-nel. Record what happens. _____________________________________________________________________________________________

4. Stop stirring. Record what happens. _____________________________________________________________________________________________________________________

5. Start stirring again. Record what happens. _____________________________________________________________________________________________________________________

6. Repeat these steps with the oobleck. _____________________________________________________________________________________________________________________

ANALYZING YOUR RESULTS1. When the ketchup was poured into the funnel, what happened? What about the oobleck? ______________________________________________________________________________

2. What happened to the ketchup when you stirred it? What about the oobleck? _____________________________________________________________________________________________________________________

3. Viscosity is a measure of how easily a fluid flows. Does the viscosity of the ketchup change as you stirred it? Did it increase or decrease? What about the oobleck?

4. When a fluid is “shear-thinning” it means it flows more easily when it’s shaken or stirred. A “shear-thickening” fluid does the opposite. Is ketchup shear-thickening or shear-thinning? What about oobleck?

_____________________________________________________________________________________________________________________

USING YOUR RESULTS TO HELP SPECTRA FIND THE KITCHENHow does the viscosity of the ketchup and the oobleck change when they are stirred?

1. Both ketchup and oobleck are shear-thinning. (The gang should go straight.)

2. Ketchup is shear-thinning and oobleck is shear-thickening. (The gang should turn left.)

3. Both ketchup and oobleck are shear-thickening. (The gang should turn right.)

Twist into a funnel Cut o�

the tip

Cut to centerTart pan

Images not to scale

APParently, this one does.

HA HA hA! Sorry!

learn how your world workscomWritten by

Rebecca Thompson, Ph.D.

Illustrated byKerry G. Johnson

American Physical Society © 2013

All Rights Reserved

MARCH • 2013

www.aps.org

TM

Documents

aps - Physics · Plastic container and lid. Steel, plastic, wooden spheres Transparency sheet. Tissue paper Plastic box. Pipette with rheoscopic fluid concentrate Black construction