How Fast is Too Fast? The way to catch a knuckleball is to wait until it stops rolling and then pick it up. - Bob Uecker © 2014, Simplify Science Select

© 2014, Simplify Science Select LLC

How Fast is Too Fast?

The way to catch a knuckleball is to wait until

it stops rolling and then pick it up.

- Bob Uecker


Learning GoalsStudents will be able to: 1) Create and interpret a

distance v. time graph.

2) Use the equation:


What we already know…The length between two points can be measured using either:

DistanceOr

Displacement

For objects moving that do NOT change direction

Distance = Displacement


What we learned in the lab…

Time is usually the independent variable.

Distance is the dependent variable.

The slope of a distance v. time graph gives speed


Timemeasures the interval between events

measured with a photogate or a stopwatch

nearly always the independent variable


Displacement (∆d) v. Distance (d)

Distance – scalar measuring the total length traveled between two points

Displacement – vector measuring the change in position between two points

Both are measurements of length measured in meters

Start Stop


Identify Variables Step #1Identify the Independent Variable AND Units The IV is the variable you change.

Identify the Dependent Variable AND Units

The DV is the variable that depends on you changing the IV


Title the Graph Step #2Title the graph using the following convention:

Dep Var v. Ind Variable for __________ Investigation

Distance v. Time for Walking Investigation


Scale the Graph Step #3Identify the MAXIMUM

and MINIMUM measurements

Count how many boxes you have on each axis (20)

MAX – MIN / # of boxes


Plot the Points Step #4

Put all of the data points on the graph.

Do NOT forget your scale


Draw the Line Step #5

Draw 1 STRAIGHT line that goes through an average

of the point

Do NOT connect the dots!


Find the Slope Step #6Look at the line NOT your

data points!

Pick two points that are easy to read

Calculate the Rise/Run for those two points


Find the Meaning of the Slope Step #7

Calculating the slope is not for fun.

The slope has to have meaning.

Rise (Distance) = Speed Run (Time)


Developing A-1A student investigates the relationship between distance a toy car and time it is allowed to roll along the floor. What would be an appropriate title for the graph?


Proficient A-2

Determine the average speed of the objects based on the graph.

0 2 4 6 8 10 120

2

4

6

8

10

12

Distance v. Time

Dist

ance

(m)

Time (s)


Proficient A-3How far will the car be at ‘b’ seconds?


Mastery A-4

Determine the average velocity between four and five seconds

0 1 2 3 4 5 60

5

10

15

20

25

30Position v. Time

Time (s)

Positi

on (m

)


Mastery A-5What time interval will the object shown below be moving the fastest?


Average Speed

The relationship between speed, distance and time can be seen in the equation:

Now you don’t have to graph every set of data to find the speed.


Speed and VelocitySpeed is distance/time.

Velocity is displacement/time

Speed and velocity are the same UNLESS the object changes direction


Average Speed Equation

Variable Name Definition SI Unit Measured

s Speed Rate of change in distance m/s RADAR/Photogate &

Rulerd distance Total length traveled m Meter stick

t time Interval between events s Photogate/stopwatch


G.U.E.S.S MethodGiven – Information problem provides

Unknown – What you are solving for

Equation – Write the equation (no numbers)

Substitution – Put the numbers in the equation

Solution – Solve for the unknown


Developing B-1Fill in the word and meaning for the acronym below:

G.U.E.S.S.

When do we use G.U.E.S.S?


Developing B-2Match the units with the variable. Circle the units if they need to be converted.

d meters

Newtonss Amperes

minutest miles per hour


Proficient B-3A car travels down a long straight 200 m road for 10 seconds. What is the average speed of the car down the road?


Proficient B-4A student walking down the hall has five minutes to

walk 150 m to their next class. What is the minimum average speed the student can have and make it to

class? (Answer in STANDARD units)


Mastery B-5 You wake up late for school one morning and walk out the door at 8:36 AM. You travel at an average of 60 kilometers per hour for the 11 km trip. If school starts at 8:45 AM will you be on time?

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How Fast is Too Fast? The way to catch a knuckleball is to wait until it stops rolling and then pick it up. - Bob Uecker © 2014, Simplify Science Select