1. Table of Contents 43 4B1 Acc. In Circular Motion (p72)
2 Making a low friction air puck
3 4A1 Rolling on an Incline Plane (p64)
28 Make a Zip Lock Bag Accelerometer
31 4A3 Classifying Motion (p69)
43 4B1 Acc. In Circular Motion (p72)
53 4B2 Acc. When speed/dir. change (p75)

2. Making A Low Friction Balloon Air Puck S-5
Created for OP
3 October 2K+3

3. FORCES & MOTION IVA1 ROLLING ON AN INCLINED PLANE
Created for OP
26 April 2K+2

4. Materials:
Inclined plane
Free‑wheeling toy car
Masking tape or chalk or movable place‑markers
meter stick
stop watch

5. 1. Adjust the inclined plane so it takes the car at least three seconds to reach the bottom. Try for four or five seconds.

6. 2. A timekeeper will call out seconds
2. A timekeeper will call out seconds. Release the car at the top of the incline at one of the seconds.

7. 3. Every time the timekeeper calls out another second, mark the incline to show where the car was at that second.

8. Measure the distance between the marks to find out how far the ball rolled during each second.
Record your measurements in the data table below.

9. Distance (in cm) Car Traveled During One Second
Trial 1st 2nd 3rd 4th 5th 1 2 3
Ave

10. 5. Calculate the average velocity for each of the time intervals
5. Calculate the average velocity for each of the time intervals. Use the average distance from above. (The elapsed time is always one second.)

11. Table of Results Time Interval Average Velocity (sec) (cm/sec) 1st 2nd
3rd
4th
5th

12. 6. What happened to the average velocity of the car as it rolled down the incline?

13. 7. How much did the average velocity change between the first and second time interval?

14. 8. How much did the average velocity change between the second and third time interval?

15. 9. How much did the average velocity change between the third and fourth time interval (if you got this data)?

16. 10. How much did the average velocity change between the fourth and fifth time interval (if you got this data)?

17. 11. Did the average velocity change by about the same amount with every passing second?
Give the value.

18. 12. Your answer to number 11 is called the rate of change of velocity.
It is the change in velocity divided by the elapsed time.

19. Its units are the units of velocity divided by the unit of time
(usually meters per second divided by seconds or centimeters per second divided by seconds;
we would say "meters per second per second").

20. The rate of change of velocity is called the acceleration
The rate of change of velocity is called the acceleration. Use your answer to number 11 and write out, with units, the average acceleration of the car as it rolled down the incline.

21. 13. When you set up the inclined plane, what do you think the acceleration of the car would have been if the end of the incline had been lifted twice as high?

22. 14. If the end of the incline had been lifted twice as high, what would you predict for the average speed during each of the time intervals?

23. 15. Repeat the experiment using twice the height for the elevated end of the incline.

24. 16. Discuss how well your new data matched your predictions
16. Discuss how well your new data matched your predictions. Include comments about the efforts of some other teams.

25. 17. For your first set of data, if the car could continue accelerating on the same incline for 10 seconds, what would you predict for its average velocity during the tenth second?

26. The acceleration of gravity on Earth is 9
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:
1 sec___ 2 sec___ 3 sec___

27. That’s all Folks

28. Force and Motion 4A3 Classifying Motion p 69
Created for OP
26 April 2K+2

29. Predict Accelerated or not? Not moving? Speeding Up?
Constant speed, st. line?
Slowing down?
Changing Direction?

30. Cart and Accelerometer
At Rest
Long Slow Push
Constant Speed
Slowing down

31. Repeat – Be More Aggressive
Cart and Accelerometer
At Rest
Long Slow Push
Constant Speed
Slowing down

32. Repeat – Be More Aggressive
What does the “trusty” accelerometer demonstrate?
How does it display the direction of acceleration?

33. Cart on Incline Going down the incline Going up the incline
Going Up and Down incline

34. Cart on Incline
What is the direction of the acceleration of a cart on a ramp?
a. Going down?
b. Going up?
c. At the top?

35. What is the “trusty” accelerometer telling us?
a. To right, speeding up
b. To right, slow down
c. To right, constant speed
d. The repeat, to left?
e. At the top of ramp?

36. Cart on Incline
15.

37. Cart on Incline
16.

38. Cart on Incline
17.

39. That’s all Folks

40. Force and Motion 4B1 Acceleration In Circular Motion 72
Created for OP
26 April 2K+2

41. Rotate on stool with “trusty” indicator perpendicular to arm.

42. 2. Rotate on stool with “trusty” indicator parallel to arm with arm outstretched.

43. 3. Rotate on stool with “trusty” indicator parallel to arm but close to body.

44. Show large accelerometer

45. 4. When an object is moving in a circle at constant speed, what is the direction of acceleration?

46. Does the acceleration depend on how far from the center it is measured?
Demo: Multi-Accelerometer

47. 6. What does “trusty” accelerometer say when it is placed on top of ones head.

48. 7. Twist “trusty” accelerometer using strings.

49. That’s all Folks

50. Force and Motion 4B2 Acceleration When Speed and Direction Change 75
Created for OP
26 April 2K+2

51. 1. “Trusty” indicator suspended by strings.

52. Force and Motion 7A2 Acceleration is Proportional to Net Force 130
Created for OP
10 November 2K + 4

53. Attach a spring scale to ____ and pull horizontally with a force of 3 or 4 Newtons.
Why doesn’t the chair accelerate?
What is the value of the net force on the chair? zero

54. Pull horizontally on the scale until the chair slides slowly at a constant speed.
Make a diagram with arrows to show:
- the force you are applying
- the force of friction acting on chair
- Label the arrows with the values of
the forces

55. If the chair moves at constant speed, the force of friction is known.
When an object is sliding at a constant speed the force of friction is at its maximum.
If the chair moves at constant speed, the force of friction is known.

56. What is the applied force? _____ What is the force of friction? ___
4. The applied force is the reading on the scale.
What is the applied force? _____
What is the force of friction? ___
What is the net force? _____

57. 4. When objects start from rest and have a constant acceleration, their acceleration can be compared by comparing the distances they travel in equal time.

58. For example, if one object travels 3 meters in 3 seconds
and a second object travels
6 meters in 3 seconds,
the second object has twice the acceleration as the first.

59. that the acceleration depends
If you take data,
you will determine
that the acceleration depends
not on the
force applied
but
on the
net force.

60. 2 Newtons larger than friction, pull the object across the table.
Using a force that is
2 Newtons larger than friction,
pull the object across the table.
Strive to keep the reading on the scale from changing.

61. the position of the object at the moment it starts to move
Have someone mark
the position of the object
at the moment it starts to move
and at the end of 2 seconds.
Measure the distance and record in the table.

62. Applied Force Net Distance Force Friction Force Traveled
(N) (N) (N) (cm) 2 4 6 8

63. Remember that accelerations can be compared by comparing distances when objects accelerate uniformly from rest.
Look at the ‘Distance Traveled’ column.
Did the acceleration double?

64. 6. Did the applied force ever get to be twice as large as the first one?
If so, did the acceleration double at the same time?

65. 7. Did the net force ever double?
Did the acceleration double at the same time?
Keep in mind that it is hard to keep the force constant so if distances are approximately twice as much, it is fair to say the acceleration doubled.

66. seem to show that the acceleration
Does your data
seem to show that the acceleration
is proportional to the
applied force
or to the
net force?

67. That’s all Folks