Mon Oct 28, 2013

1. Test (need pencil & ruler)

2. Asst: Notes pages 146- 152; make sure you write the PAGE NUMBER of the book for each part of the notes!!

Tues October 29

1. Turn in anything from graphing unit (worksheets, anything else?)

2. Lecture notes: • Horizontally-shot projectiles

3. Asst: problems 2-9**Very short unit; Nov 8th (next Friday)

is the unit test!!

MOTION OF A “PROJECTILE” or an object moving in 2 dimensions:

• The path an object follows is called a _________. The shape of this path is a _________. (these are vocab words on your next test!)

• The motion of a projectile is described in terms of position, velocity, and acceleration. These are all vectors and are independent of each other.

POSSIBLE EQUATIONS:(gee, do these look familiar?)

d=

d=

vF=

vF2=

WHAT TO FIND IN “TYPE A” (horizontally-shot) PROJECTILES?

• RANGE (dx)

– Displacement from the beginning of the path to the end in the x direction.

• FINAL TOTAL VELOCITY (vFT)

– This is a vector quantity and has direction and magnitude. Add vFx and vFy together vectorally.

YOU MUST MAKE TWO LISTS:VARIABLES IN THE X&Y

DIRECTIONS

x y

vox = (given) voy = (if shot horiz./type A)

vFx = ? vFy = ?

dx = ? (“range”) dy = (given; always neg ht for horiz./type

A)

ax = (always for projectile) ay = (always for proj.)

t = ? (no subscript, same in x&y)t = ? (no subscript, same in x&y)

range = ? vFT = ?

EXAMPLE A:A projectile is shot horizontally at 10.0 m/s from a height of 100. meters. What is its range and final

velocity?

velocity: 10 m/s

height: 100 m X

vox =

dx = (range)

ax =

vFx =

t =

Y

voy =

dy =

ay =

vFy =

t =

Step 1 – list your variables (10 points on the test)

Steps 2-4, SOLVE:

• dy= voyt + ½ayt2

t = _____ s

• vFy= voy + ayt

vFy= -_____ m/s

(but you still haven’t found vFtotal yet! ...)

2. 4.

3. • dx= voxt + ½axt2

so range = _____ m

3 points for each of these steps on the test!

When solving for the total final velocity of objects shot horizontally, it will always be the vector sum of the final velocities @ some degree below the horizontal.

Use the Pythagorean theorem to get the magnitude of the resultant and inverse tangent to get the degree:

__ _2 + __ _2 = resultant2

tan-1 ( / ) = degree

vFtotal = ________@ _____ “below the horizontal”

FINDING THE TOTAL FINAL VELOCITY

m/s

m/s

Step 5:

Note: vFx same as vox because ax=0 !

6 points for showing diagram & work & answer on the test!

Now do Asst A, numbers 2-10 all by yourself with a chart/table of givens!

(Notice the answers are also provided!)

5 steps:

1) Make lists

2) Find time with y list

3) Find range (dx) with x list

4) Find vfy with y list

5) Find vf total with vectors

Wed Oct 30

1. Lecture Notes – projectiles type B2. Asst: “day 3” #2-10 on asst sheet (Written on the asst sheet, but FYI ....)Note # 10 is a graph & you’ll need a piece of graph

paper.You are going to be plotting the trajectories (which

are all parabolas) of questions 1-9 and there is an example of what you should get on the asst sheet. Make sure you use the WHOLE sheet of paper to make a BIG graph.

WHAT TO FIND IN “TYPE B” (shot-at-an-angle) PROJECTILES?

• RANGE (dx)– Displacement from the beginning of the path to the

end in the x direction.

• FINAL TOTAL VELOCITY (vFT)– This is a vector quantity and has direction and

magnitude. Add vFx and vFy together vectorally.

• MAXIMUM HEIGHT (dy – kinda)– Displacement from the beginning of the path to the

MIDDLE in the y direction.– THIS REQUIRES A THIRD SEPARATE LIST!!!!

EXAMPLE B:Suppose a ball is launched at an initial velocity of

10.0 m/s at 5.00° above the horizontal. Find the max ht, range, and total final velocity.

range = ? vF total = ?

max ht = ?

10.0

m/s

at 5

.00°

Step 1: YOU MUST MAKE TWO LISTS: VARIABLES IN THE X&Y

DIRECTIONS for the range:(10 points on the test)

x y

vox = voy =

vFx = vFy =

dx = (“range”) dy = (always 0 for type B)

ax = (always for projectile) ay = (always for proj.)

t = (no subscript, same in x&y) t = (no subscript, same in x&y)

5.010

.0 m/s

Make sure you

understand WHY this is true!

2. Start by solving for time, using the y components.

dy = voyt + ½ayt2

(we divided the whole equation by t)

t = _______ seconds 3. Now you can solve for dx (range) using the x components.

dx = voxt + ½axt2

dx =

dx =

dx = ____, so the range is ________

3 points for each of these steps on the test!

When solving for the total final velocity of objects shot horizontally, it will always be the vector sum of the final velocities @ some degree below the horizontal.

OK, so solve for the resultant (hypotenuse) and the angle (using inverse tangent) on your paper right now!

Because its symmetric we know the total final velocity will be the same as the initial speed BUT the OPPOSITE direction.

The initial velocity was: 10.0 m/s at 5.00° above the horizontal.

Thus, the final velocity is: 10.0 m/s at 5.00° below the horizontal.

FINDING THE TOTAL FINAL VELOCITY

Note: vFx same as vox because ax=0 !10.0cos5.0°

10.0

sin5

.0°

Note: vFy same as NEGATIVE voy because it’s a symmetric parabola! (When it returns to it’s initial launch

position, the vertical speed is the same as it was at launch, but it’s direction is reversed, giving it a different velocity.) Step 4: 3 points for stating the vF total

on the test, and no points for the work - since none is required!

Step 5: Make a list of the y values AT THE MAXIMUM HEIGHT.

It is not necessary to list the x components at the maximum height.

y-max htvoy =

ay =

dy-max =

vfy =

t = who cares?!?!

Do NOT use time to find the max height – ever! No bad habits in Physics, as this will not work for Type C projectiles

Step 5 cont: Remember kinematics!

vfy2 = voy

2 + 2aydy-max

dy-max = _______, so the maximum height is ________.

Summary of steps for Type B

1. Make x & y lists for range

2. Find time using y list

3. Find range using x list

4. STATE vF Total

5. Make new y list for max ht

6. Find max height

Now do Asst B, numbers 2-10 ALLall by yourself with a chart/table of givens!(Notice the answers are given.)

Note # 10 is a graph & you’ll need a piece of graph paper.You are going to be plotting the trajectories (which are all parabolas) of questions 1-9 and there is an example of what you should get on the asst sheet (& below). Make sure you use the WHOLE sheet of paper to make a BIG graph:

Ms. Bourke - Mon Nov 4 (no school Thurs/Fri

last week; in math lab Mon & Tues)

1. Discuss (& start) tonight’s HW part b. (see next slide)

2. Start Computer Activity: Interactive Physics3. Asst: Day 4 (what’s written below is ALSO on the asst sheet, so

you don’t need to copy it.)

(a) Problems on “Motion in Two Directions” ditto: on the backside, on the bottom, part G problems 1-3. DO THESE ON A SEPARATE SHEET, not on the wksht!! #1 is a straight-forward Type A (horizontally shot) problem just like day 2. Find the range and final (total) velocity. #2 is a straight-forward Type B problem just like day 3. Find the range, maximum height, and final velocity. #3 is a Type A (horizontally shot) problem of a slightly different nature. First, find the time using the y-list, just like usual. Then, use the x-list to get the initial velocity in the x (the range is given).

(b) See instructions on the back of asst sheet “Day 4”. You will also need a piece of graph paper.

Test is Nov. 8th Binders due?

Ms. Lewis - Physics Mon Nov 4 (no school Thurs/Fri last week; Eng or SS lab, but oly 1 day)

1. Immediately start Computer Activity: Interactive Physics

– Open up Interactive Physics. If you get a message “Do you want to restart your computer now?” – choose NO, and relaunch the program.

– Pull down View, Workspace and make sure rulers and gridlines are checked.

– Pull down View, View Size and make the Window width 150 meters.– Draw a circle in the upper left of the screen (like in the upper left-most

grid, about a third the size of a grid.)– Continue following the directions on the sheet ….

2. Asst: Worksheet parts A-F (G is part of tomorrow's HW); YES, write on it!

“Day 4” Asstpart A is to do problems G1-3 on a separate sheet of

paper, Part B is to ….Get out a blank piece of paper, and …

Then you will do pebble 2, and pebble 3THEN, you will graph the 3 pebbles’ paths:

Worksheet #1-3 hints:

• #1 is a straight-forward Type A (horizontally shot) problem just like day 2. Find the range and final (total) velocity.

• #2 is a straight-forward Type B problem just like day 3. Find the range, maximum height, and final velocity.

• #3 is a Type A (horizontally shot) problem of a slightly different nature. First, find the time using the y-list, just like usual. Then, use the x-list to get the initial velocity in the x (the range is given).

Interactive Physics (see handout)1. Open up Interactive Physics. If you get a message “Do you want to restart

your computer now?” – choose NO, and relaunch the program.2. Pull down View, Workspace and make sure rulers and gridlines are

checked.3. Pull down View, View Size and make the Window width 150 meters.4. Draw a circle in the upper left of the screen (like in the upper left-most grid,

about a third the size of a grid.)5. Click once on the circle to select it, then pull down Window, Appearance.

Make sure “Track Center of Mass” and “Track Outline” have checkmarks.6. Pull down World, Tracking and track the ball every 8 frames.7. Run your simulation, being careful to stop it right before it goes to the

bottom of the screen.8. Every time you want to change

something about the sim, you must press “Reset” in the upper toolbar. So press Reset.

Keep following the directions ….

Monkey problem p.164 #44

Ms. Bourke Tues Nov 5 (2nd day in math lab)

1. Interactive Physics – finish

• No more class time tomorrow; due Friday 4:30 PM (all 3 files saved in your I drive)

2. Asst: Day 5:– The “Motion in Two Directions” wksht: on the

front-side parts A (multiple-choice), B (short answer), and C (fill-in); and on the back parts D-F (the 10 short conceptual problems). All of these answers you may write ON THE WKSHT.

Test is Nov. 8th

Binders due?

Mrs. Lewis, 2013: (only 1 day in lab)no school Thurs & Fri 10/31 & 11/1

Monday Nov 4th

1) Computer lab – Interactive Physics2) HW = Worksheet parts A-F

Tuesday Nov 5th 1) Warm-up:

a. List all 4 kinematics equations.b. A stone is thrown horizontally at a speed of 5 m/s from the top

of a cliff 76 meters high. Set up the x & y lists to find the time, range and final velocities. DO NOT SOLVE!

c. A player kicks a football from ground level with a velocity of 27 m/s at an angle of 15 degrees above the horizontal. Set up the x & y lists to find the time and range. Set up the additional y list to find the max height. DO NOT SOLVE!

2) pass back graphing, organize binders, hand-up HW • **go over day 4 graph

3) Explain/start HW….4) HW = Day 4 AND Worksheet Problems part G # 1-3 on a

SEPARATE SHEET of paper!

Test is Nov. 8th

Binders due!

Wed Nov 6

1. Go over day 3 graph & collect

2. Go over Day 4 (watch demo, take notes) & G1-3 (answers); collect

3. Draw d, v, and a vectors together

4. Turn in review wksht – Start to go over?

5. Asst: Day 6: More Projectile Problems 1-9 (but do # 1 & 7 first)

Test is Nov. 8th;

Binders due!

Graph from day 2 asst:

Trajectories of a Projectile

0

5

0 10Range

He

igh

t

5 degrees

15 degrees

25 degrees

35 degrees

45 degrees

55 degrees

65 degrees

75 degrees

85 degrees

Similar graph to day 4 asst:

dx vectors and dy vectors:

vx vectors and vy vectors:

ax vectors and ay vectors:

Thurs Nov 7Unit Test (whole hour)/Quiz (only 50 pts) is Tomorrow!

1. Go over Review wksht - already turned in

2. Answers to review problems (grade #1 & #7 like a quiz in red pen)

3. Asst: Day 7:• Redo 3 problems of EACH type A and B - any you

choose• plus study “extra stuff” (wrksheet & back of vectors)• PRINT OFF STUDY GUIDE, read & answer questions!

Fri Nov 8 You may copy this down AFTER the test, if you’d like!

1. Projectiles unit test/quiz (you have most of the hour, but the test is only 50 pts instead of the usual 100) MAKE SURE YOUR CALCULATOR IS IN DEGREES!

2. AFTER test: Turn in anything without a grade-mark (d,v,a vectors sheet, plus …???)

3. Asst: a) GUIDED Notes pp 88-107 & 126-132; this means you have a 2-sided worksheet to fill out as you read the text….

• Sure, you could always copy someone else’s Guided Notes, and no, we’d probably never know, but if you do so you would be missing an IMPORTANT LEARNING OPPORTUNITY about our next unit & all of the concepts we will be covering!