Daily Info Activities
For
Forces and Motion
Created for B-W
Middle School Physics Course
By
Dick Heckathorn
9 Jan 2K + 11
1
Rationale
Why teach Forces and Motion first?
1B3 p 19 Traveling Washer
A.. 2 cm N
B. 5 cm E
C. 5 cm N
D. 3 cm W
E. 4 cm N
F. 6 cm E
G. 3 cm S
Total Distance
Finish
28 cm
Start to Finish
11.3 cm
Distance Traveled
28 cm
Start
Displacement 11.3 cm at angle of E 45o N
Displacement components are 8 cm E 8 cm N
8
1B1 Where is it? p 21
How do we locate an object in 3-D space?
Step 1
Write directions from the door
to an object in the room
Step 2
Have blindfolded person follow written
direction read by person not writing it.
10
1B2 p 23
The Treasure Hunt
Handout Cards
Start in Doorway
North is….
11
Floor 1
Floor 2
3A4 p 39
Can You Walk at a Constant Speed?
Stickers on floor
They are equal distance apart
There are 4 different intervals.
23
3A4 p 39
Can You Walk at a Constant Speed?
S
1
2
3
4
Starter at S
Timers at 1, 2, 3, 4
Starter signals start – all watches start
Each timer stops the watch as person passes.
Walker walks back getting times.
Rotate positions until all have walked.
24
3B1 pp 45
Velocity Isn’t Speed
Time yourself walking from A to B
Time yourself from B to A
Complete worksheet
Discuss traveling on turnpike
How to estimate speed of car going faster than you!
25
3A5 p 41
How Fast Can You Run?
Homework
You can walk, crawl, hop etc. to
travel a known distance.
You might involve your friends.
26
3A6 p 43
How Fast Is It?
Homework
Any web sites relative to this activity?
27
3A6D Page 43
How Fast is It?
Any questions/comments?
28
3B1 pp 45
Velocity Isn’t Speed
Share your speed values from A to B
and then B to A
Were they the same?
Share your velocity values from A to B
And the B to A
Were they the same?
29
3B2 page 49
Walking Around a Square Lab
Do as Homework before class
Discuss results in class
30
3B2 page 49
B
C
2m
Distance A to B? 2 m
Displacement A->B? 2 m N
Distance A to B to C? 4 m
Displacement from A-B-C?
A
2.83 m N 45oE
D
Distance from A to B to C to D? 6m
Displacement from A to B to C to D? 2 m E
Distance from A to B to C to D to A? 8m
Displacement from A to B to C to D to A? 0
31
3B2 page 49
t = 1 sec to go 2 m
Distance A to B? 2 m
Displacement A->B? 2 m N
Distance A to B to C? 4 m
2 m/s
2 m/s N
2 m/s
Displacement from A-B-C? 2.83 m N 45oE 1.42 m/s N45oE
Distance from A to B to C to D? 6m
Displacement from A to B to C to D? 2 m E
Distance from A to B to C to D to A? 8m
Displacement from A to B to C to D to A? 0
2 m/s
2 m/s E
2 m/s
0
32
3C1D page 53
Interstate Highway Story
Do as Homework before class
Any Questions?
33
3C2D page 55
Speed and Velocity
Each table – Stomper Car, String
Fasten string to car.
Put loop in other end of string.
Hold string using pencil
Turn Car on and watch it go.
(Make sure it goes in a circle)
34
3C2D page 55
Speed and Velocity - 2
Is car going at constant speed?
Is the car going at constant velocity?
At A?
1
At B?
At C?
2
4
At D?
3
35
3C2D page 55
1
2
4
3
4. What is instantaneous velocity at point 1?
5. What is inst. velocity at point 2?
Did velocity change?
6. Is velocity constant as object moves in circle?
36
3B1A page 47
Block Walk
Read before class
Do in class
Can you do the acceleration part?
37
Homework
P 45 #5 Speed/velocity on 1 way street?
#6 Cruse control set – velocity vs speed
p 50 #6d My error
#7 Earth average velocity for year?
Average velocity for ½ year?
39
Workshop Leaders Guide p63
Acceleration
Read this to get an idea as to what this
section is about.
Any Questions?
40
Workshop Leaders Guide p63
Acceleration
What is rate of change of velocity?
change in velocity / time (acceleration)
Speeding up is called?
positive acceleration
Slowing down is called:
negative acceleration
Deceleration is not a physics word
41
4A1 page 65
Rolling on an Inclined Plane
Cars
Track
Stop watches
Stickers
Meter stick?
Pulley
string
42
Workshop Leaders Guide p63
Acceleration
The units of acceleration are:
change in velocity / time
(cm/sec) / (sec)
(cm/sec/sec)
(cm/sec2)
43
4A1 page 65
Rolling on an Inclined Plane
- Questions? Comments?
44
Rolling on an Inclined Plane
110.6
Position (from beginning to end of each interval (cm)
B
C
D
99.5
83.0
62.8
E
38.4
0
Time (from beginning to end of each interval (ticks)
5
10
15
20
A
11.1
5
2.22
Interval distance (cm)
16.5
20.2
Interval time (ticks)
5
5
Average Velocity (cm/tick)
3.30
4.04
24.4
5
4.88
Change in Average Velocity (cm/tick/tick) (acceleration)
1.08
.74
.84
4A1 p 65
6. What is the average velocity of the car
rolling down the plane?
Now much did the velocity change between the
7. 1st and 2nd interval? ___ cm/sec
8. 2nd and 3rd interval? ___ cm/sec
9. 3rd and 4th interval? ___ cm/sec
11. How do the changes compare?
12. These changes are called: acceleration
The average change is:
46
4A1 p 65
15. For your first set of data, if the car could continue
accelerating on the same incline for 10 intervals,
what would you predict for its average velocity
during the tenth interval?
16. The acceleration of gravity on Earth is 9.8 meters
per second per second. If a rock is dropped from
a sufficient height, how fast will it be going after:
One second?
_______
Two seconds?
_______
Three seconds? _ ______
47
4A1 p 65
6. What is the average velocity of the car
rolling down the plane?
Now much did the velocity change between the
7. 1st and 2nd interval? ___ cm/sec
8. 2nd and 3rd interval? ___ cm/sec
9. 3rd and 4th interval? ___ cm/sec
11. How do the changes compare?
12. These changes are called: acceleration
The average change is:
48
4A2D page 69
Speeding Up and Slowing Down
Homework
Do before class
Will discuss in class
49
4A2
1.It is a common error to confuse the speed
of an object with its acceleration; many
people say that something with a large
acceleration (like a car that can go from
zero to 60 miles per hour in 4 seconds) is
“fast”. Of course, such a car may be able
to go very fast indeed, but not necessarily.
Conversely, some things can go very fast
but have a small acceleration.
4A2
2.List two or three things that may have a
large acceleration but do not usually have
large speeds. (You will need to decide just
what ‘large speed’ means.) Discuss your
decision and your list with the class.
4A2
3.List two or three things that reach large
speeds, but don’t necessarily have large
accelerations. (Your benchmark for ‘large
speed’ need not be the same as for
number 2.) Discuss your decision and your
list with the class.
Speeding Up and Slowing Down
4. Rank the following from small to large acc.
a. Arrow being shot from a bow.
b. Falling rock.
c. Throwing a baseball
d. Driven golf ball.
e. Space shuttle taking off.
f. ‘Putting’ a shot.
g. Family car starting off.
h. Dragster starting off.
5. Which has the greatest maximum speed?
6. Does it have the greatest acc.?
53
Speeding Up and Slowing Down
7. Which has the greatest acceleration?
A baseball being thrown or
the thrown baseball being caught
A falling rock or
a falling rock hitting the ground?
A track runner starting off or
the track runner stopping at the end of the race
A car stopping for a red light from 40 mi/hr or
a car hitting a tree at 40 mi/hr?
54
Speeding Up and Slowing Down
8. A baseball is thrown at 90 miles per hour. If it
take 0.5 sec to accelerate the ball, what is the
acceleration?
180 miles per hour per second
180 mi/hr/sec
mi
180
hr  sec
8. A baseball is thrown at 90 miles per hour. If it take
0.1 sec to stop the ball, what is the acceleration?
900 mi/hr/sec
55
Construction
Zip Lock Accelerometer
1. Tape baggie to inside of one cardboard
- use masking tape
2. Tape 2nd cardboard to first. (bottom, sides)
- use duct tape
3. Punch hole in sides at top
4. Insert large paper clips
5. Fill half full with colored water
- keep cardboard dry
56
Classification Motion p 71
9. Set up my accelerometer on long ramp.
- What is acceleration
- rolling down the ramp?
- slowing down going up ramp?
- What is the acceleration at the top
when the cart goes up and down?
59
Classification Motion p 71
14. The acceleration is to the right when:
a. moving right and speeding up
b. moving right and slowing down
c. moving right at constant speed
d. moving left and speeding up
e. moving left and slowing down
f. moving left at constant speed
60
Classification Motion p 71
15. Object moving to right: when acc. = 0?
- when the speed is constant
16. Object moving right, when acc. to right?
- when it is speeding up
17. Object moving right, when acc. to left?
- when object is slowing down
or after stopped and speeding up to left
61
Workshop Leaders Guide p 91
Inertia
- What is one of the most tenacious
misconceptions?
- In part A we will investigate: objects at rest
- In part B we will investigate: objects in
motion with no propelling force
64
Ch 4 End Of Chapter Questions
9–4
11-3
13 – 2
7
12
14
15
18
20
22
24
25
27
29
31
5A1F p 93
Motion and Force
Aristotle 384 - 322 BC (3 motions)
- natural
- made out of earth, fall to earth
- holy - rose to heaven
- no motion, no explanation needed
- unnatural – required explanation
66
5A1F p 93
Motion and Force 2
Aristotle 384 - 322 BC
- Earth at center of the universe
- What are your thoughts?
- Do you think like, agree with Aristotle?
67
5A1F p 93
Motion and Force 3
Galileo 1564-1642
- thought process – rolling ball down plane
1. object at rest:
object in motion:
Summary: no force  no acc. force  acc
2. acceleration  sum all forces (net force)
3. F1 on 2 = - F2 on 1
68
5A1F p 93
Motion and Force 4
We have said there are two types of motion
- non-accelerated motion
- will see no cause, no explanation for this
to happen Fnet = 0
- accelerated motion
- requires a cause, a force a  Fnet
Last sentence: change = to ≠
69
5A2 p 93
The Coin and The Glass
Homework
Give out 3x5 card
70
1.1 Newton’s First Law
- 1st law states that an object at rest stays at
rest and an object stays in motion unless
another force acts on it
- Objects tend to either stay in motion or at
rest unless some force acts upon them
79
1.2 Inertia and Mass
- Newton’s 1st law - No force is needed to
keep an object in motion
- Inertia is a resistance to change in v, a
- Inertia is a quantity that is entirely
dependant upon the mass of an object.
- I think that an object will stop moving
because the object does not have any
more force exerted on it.
80
1.2 Inertia and Mass
- ….a force of friction is what is needed to
stop an object, not an actual force
- It also talks about the correlation between
mass and inertia
- inertia is the tendency of a particular
object to resist changes in its own velocity
- Inertia is the resistance to change in its
normal state of motion
81
1.2 Inertia and Mass
- Inertia is the only thing dependent on
mass.
82
1.2 Inertia and Mass
1. Imagine a place in the cosmos far from all
gravitational and frictional influences.
Suppose that you visit that place (just
suppose) and throw a rock. The rock will
a. gradually stop.
b. continue in motion in the same direction
at constant speed.
84
1.2 Inertia and Mass
2. A 2-kg object is moving horizontally with a
speed of 4 m/s. How much net force is
required to keep the object moving at this
speed and in this direction?
85
1.2 Inertia and Mass
3. Mac and Tosh are arguing in the
cafeteria. Mac says that if he flings the
Jell-O with a greater speed it will have a
greater inertia. Tosh argues that inertia
does not depend upon speed, but rather
upon mass. Who do you agree with?
Explain why.
86
1.2 Inertia and Mass
4. Supposing you were in space in a
weightless environment, would it require a
force to set an object in motion?
87
1.2 Inertia and Mass
5. Fred spends most Sunday afternoons at
rest on the sofa, watching pro football
games and consuming large quantities of
food. What effect (if any) does this practice
have upon his inertia? Explain.
88
1.2 Inertia and Mass
6. Ben Tooclose is being chased through the
woods by a bull moose which he was
attempting to photograph. The enormous
mass of the bull moose is extremely
intimidating. Yet, if Ben makes a zigzag
pattern through the woods, he will be able
to use the large mass of the moose to his
own advantage. Explain this in terms of
inertia and Newton's first law of motion.
89
1.3 State of Motion
- keeps on doing what they’re doing unless
acted upon by a force
- Inertia is a resistance to change in v, a
- An object at rest has a velocity of zero,
and that object will not change its state of
motion unless another force acts on the
object. (demo – block and scales)
- The state of an object (either in motion or
not in motion, which would be at rest.)
91
1.3 State of Motion
93
1.3 State of Motion
2. A 4.0-kg object is moving across a
friction-free surface with a constant
velocity of 2 m/s. Which one of the
following horizontal forces is necessary to
maintain this state of motion?
a. 0 N
b. 0.5 N
c. 2.0 N
d. 8.0 N
94
1.3 State of Motion
4. If the forces acting upon an object are
balanced, then the object
a. must not be moving.
b. must be moving with a constant velocity.
c. must not be accelerating.
d. none of these
95
98
99
100
2.2 Types of Forces
- Ffriction = µ Fnormal
105
2.4 Determining Net Force
- Formulas, Formulas, Formulas
110
5B1 p 97
Inertia
2. What force pushes forward on the coin?
none
3. What force pushes backward on the coin
friction
113
5B1 p 97
Inertia 2
4. What force - you feel as car comes to stop
5. What force pushes you forward? None
6. What force pushes you backward? S-belt
7. In #4 direction of acceleration is: backward
8. How does direction compare: acc. vs force
9. Could cause of force in #2 be inertia? no
10. When you throw a ball, what keeps it
moving?
114
5B2F page 99
-
Newton’s 1st Law – Inertia 1
refers to stubbornness of matter
objects want to say as they are
inertia is a property of matter-identifies this
it is not a force
if there is no net force – no acceleration
if there is a net force – an acceleration
115
6A3D page 117
The Undercover Scale
Will be done in class
121
6C1 page 123
How Strong Is Friction?
Examine Block Pulled
by Balance
Look at forces
Look at

Ff
Fn
124
Look at Vectors
Crossing River Problem
125
7A2 p139
Acceleration is Proportional to Net Force
128
7A3D p143
Paper and Book Drop
129
130