Name: 
 

Physics 12 - Unit 1 Test


True/False
Indicate whether the sentence or statement is true or false.
 
 
For questions 1 to 6, consider a ball of mass m, thrown at an angle above the horizontal and undergoing projectile motion under negligible air resistance.
 

1. 
The time for the ball to rise equals the time for the ball to fall to the same horizontal level.
 

2. 
The net force on the ball at the top of its flight is zero.
 

3. 
The acceleration of the ball on the way up equals the acceleration on the way down.
 

4. 
After leaving your hand and before landing, the speed of the ball is at a minimum at the top of its trajectory.
 

5. 
      The magnitude of the horizontal component of the velocity of the ball just before impact exceeds the magnitude of the horizontal component of the velocity just after the ball leaves your hand.
 

6. 
The magnitude of the acceleration of the ball at the top of its trajectory equals the ratio of the weight of the ball to its mass.
 
 
or questions 7 to 12, assume that you are twirling a small rubber stopper of mass m (at a constant speed v) tied to a string in a vertical circle as shown in Figure 1.
p12u1_files/i0090000.jpg

Figure 1
For questions 7 to 12
 

7. 
At position 3, the direction of the instantaneous acceleration is westward and the direction of the instantaneous velocity is upward.
 

8. 
The vector quantity p12u1_files/i0110000.jpg is closest to the instantaneous acceleration as the stopper moves from position 6 to position 1.
 

9. 
The magnitude of the tension in the string at position 1 exceeds the magnitude of the tension at position 4 by an amount equal to mg.
 

10. 
At position 5, the force that causes the stopper to accelerate toward the centre of the circle is the sum of the force of tension in the string and a component of the force of gravity on the stopper.
 

11. 
If you release the ball at the instant it reaches position 1, the instantaneous velocity of the stopper just after the release will have a small upward component and a large eastward component.
 

12. 
For a constant radius and frequency of revolution of the stopper, the magnitude of the centripetal acceleration is directly proportional to m.
 

Multiple Choice
Identify the letter of the choice that best completes the statement or answers the question.
 
 
Questions 13 to 18 relate to the situation in Figure 2, in which a child on a toboggan (a system of total mass m) accelerates down a hill of length L inclined at an angle q to the horizontal in a time interval p12u1_files/i0170000.jpgt. The +x and +y directions are labelled on the diagram. Assume that friction is negligible unless indicated.
p12u1_files/i0170001.jpg

Figure 2
For questions 13 to 18
 

13. 
The magnitude of the child’s acceleration down the hill is
a.
p12u1_files/i0180000.jpg
b.
p12u1_files/i0180001.jpg
c.
g sin p12u1_files/i0180002.jpg
d.
g cos p12u1_files/i0180003.jpg
e.
g tan p12u1_files/i0180004.jpg
 

14. 
The magnitude of the child’s average velocity is
a.
p12u1_files/i0190000.jpg
b.
p12u1_files/i0190001.jpg
c.
p12u1_files/i0190002.jpg
d.
p12u1_files/i0190003.jpg
e.
p12u1_files/i0190004.jpg
 

15. 
The magnitude of the force exerted by the toboggan on the hill is
a.
mg
b.
mg cos p12u1_files/i0200000.jpg
c.
mg sin p12u1_files/i0200001.jpg
d.
mg tan p12u1_files/i0200002.jpg
e.
p12u1_files/i0200003.jpgmg sin p12u1_files/i0200004.jpg
 

16. 
If the child starts from rest and accelerates uniformly down the hill, the time required to reach the bottom of the hill is
a.
Lg sin p12u1_files/i0210000.jpg
b.
2Lg sin p12u1_files/i0210001.jpg
c.
p12u1_files/i0210002.jpg
d.
p12u1_files/i0210003.jpg
e.
p12u1_files/i0210004.jpg
 

17. 
If p12u1_files/i0220000.jpgav is the average velocity and p12u1_files/i0220001.jpg is the instantaneous velocity, then at the halfway point in the journey down the hill
a.
|p12u1_files/i0220002.jpgav| = |p12u1_files/i0220003.jpg|
b.
|p12u1_files/i0220004.jpgav| > |p12u1_files/i0220005.jpg|
c.
|p12u1_files/i0220006.jpgav| < |p12u1_files/i0220007.jpg|
d.
|p12u1_files/i0220008.jpgav| and |p12u1_files/i0220009.jpg| can be compared only if we are given numerical data.
e.
p12u1_files/i0220010.jpgav  and p12u1_files/i0220011.jpg cannot be meaningfully compared, since the object in question is on an inclined plane .
 

18. 
If the situation in Figure 2 is changed so that there is a coefficient of kinetic friction mK between the toboggan and the hill, then the magnitude of the child’s acceleration down the hill is
a.
g(sin p12u1_files/i0230000.jpg p12u1_files/i0230001.jpg mK cos p12u1_files/i0230002.jpg)
b.
g(sin p12u1_files/i0230003.jpg + mK cos p12u1_files/i0230004.jpg)
c.
p12u1_files/i0230005.jpg
d.
g(mK cos p12u1_files/i0230006.jpg p12u1_files/i0230007.jpg sin p12u1_files/i0230008.jpg)
e.
none of these
 

19. 
A car of mass m collides head-on with a truck of mass 5m. If p12u1_files/i0240000.jpgC®T and p12u1_files/i0240001.jpgT®C are the forces respectively exerted during the collision on the car by the truck and on the truck by the car, then
a.
|p12u1_files/i0240002.jpgT®C| > |p12u1_files/i0240003.jpgC®T|
b.
|p12u1_files/i0240004.jpgT®C| < |p12u1_files/i0240005.jpgC®T|
c.
|p12u1_files/i0240006.jpgT®C| = |p12u1_files/i0240007.jpgC®T|
d.
|p12u1_files/i0240008.jpgT®C| = 0
e.
p12u1_files/i0240009.jpgC®T and p12u1_files/i0240010.jpgT®C cancel because they are in opposite directions
 

20. 
A monkey throws a walnut from a tree, giving the walnut an initial velocity of 2.5 m/s [down]. Air resistance is negligible. After being released, the walnut experiences an acceleration of
a.
9.8 m/s2 [up]
b.
9.8 m/s2 [down]
c.
less than 9.8 m/s2 [down]
d.
more than 9.8 m/s2 [down]
e.
zero
 

21. 
A rocket of mass m is at a distance 3rE from Earth’s centre when its engines are fired to move it to a distance 6rE from Earth’s centre. Upon reaching its destination, its new mass is p12u1_files/i0260000.jpg since fuel is consumed in the burn. The ratio of Earth’s gravitational force on the rocket at the first location to the gravitational force on the rocket at the second location is
a.
8:1
b.
4:1
c.
2:1
d.
1:4
e.
1:8
 

22. 
Which of the following is a list of all the forces that act on a satellite in circular orbit around Earth?
a.
the force due to the satellite’s motion and the force of gravity toward Earth
b.
the force due to the satellite’s motion, the centrifugal force, and the force of gravity toward Earth
c.
the centrifugal force and the force of gravity toward Earth
d.
the centripetal force and the force of gravity toward Earth
e.
the force of gravity toward Earth
 

23. 
A stunt airplane flies in a vertical circular loop of radius r at a constant speed. When the airplane is at the top of the loop, the pilot experiences an apparent weight of zero. The speed of the airplane is
a.
2gr
b.
gr
c.
p12u1_files/i0280000.jpg
d.
p12u1_files/i0280001.jpg
e.
p12u1_files/i0280002.jpg
 

24. 
A 9.5-kg box is initially stationary on a horizontal table. The coefficient of kinetic friction between the table and the box is 0.49. The coefficient of static friction is 0.65. The magnitude of the minimum force needed to set the box into motion is
a.
4.7 N
b.
6.2 N
c.
93 N
d.
61 N
e.
46 N
 

Completion
Complete each sentence or statement.
 
 
      State the number of significant digits in each measurement or answer of the operation:
 

25. 
0.0501 N _______
 

 

26. 
3.00 p12u1_files/i0330000.jpg 105 km/s _______
 

 

27. 
25.989 m + 25.98 m + 25.9 m + 25 m _______
 

 

28. 
65.98 m p12u1_files/i0350000.jpg 11.5 s p12u1_files/i0350001.jpg 2.0 s _______
 

 

Matching
 
 
Beside each number, place the letter that matches the best choice. Use the choices listed below.
a.
directly proportional to
b.
inversely proportional to
c.
proportional to the square of
d.
inversely proportional to the square of
e.
proportional to the square root of
f.
inversely proportional to the square root of
g.
independent of
 

29. 
For an object moving at a constant velocity, the time interval needed to cover a certain displacement is _______  the velocity.
 

30. 
When a ball is undergoing projectile motion, the horizontal motion is _______  the vertical motion.
 

31. 
For a car that starts from rest and undergoes constant acceleration, the time interval to cover a certain displacement is _______  the displacement.
 

32. 
On the surface of Earth, your weight is _______  the mass of Earth.
 

33. 
For an object that remains stationary on a horizontal surface, the magnitude of the static friction is _______  the magnitude of the horizontal force applied to the object.
 

34. 
For an object undergoing uniform circular motion with a constant radius, the magnitude of the centripetal acceleration is _______  the speed.
 

35. 
For an object undergoing uniform circular motion with a constant radius, the force that causes the centripetal acceleration is _______  the period of revolution of the object.
 

Short Answer
 
 
      Convert the following measurements:
 

36. 
109 km/h = _______  m/s
 

37. 
7.16 p12u1_files/i0480000.jpg 104 km/min = _______  m/s
 

38. 
3.4 mm/s2 = _______  m/s2
 

39. 
5.7 cm/(ms)2 = _______  m/s2
 

40. 
4.62 p12u1_files/i0510000.jpg 10-3 (km/h)/s = _______  m/s2
 
 
Beside each number, place the word, number, phrase, or equation that completes the sentence(s).
 

41. 
A windsock indicates _______ .
 

42. 
The three principal controls a car has for regulating acceleration are _______ , _______ , and _______ .
 

43. 
You are facing southward when suddenly a snowball passes in front of your eyes from left to right. The snowball was thrown from some distance away with an initial horizontal velocity. The direction of the instantaneous velocity is now _______ . The direction of the instantaneous acceleration is now _______ .
 

44. 
If the direction of an object undergoing uniform circular motion is suddenly reversed, the direction of the centripetal acceleration is _______ .
 

45. 
If p12u1_files/i0570000.jpgLM is 26 m/s [71° W of S], then  p12u1_files/i0570001.jpgML is _______ .
 

46. 
_______ = p12u1_files/i0580000.jpgCD + p12u1_files/i0580001.jpgDE
 

47. 
The horizontal acceleration of a projectile is _______ .
 

48. 
The acceleration of an object falling (vertically) through the air at terminal speed is _______ .
 
 
      Using L, M, and T for the dimensions of length, mass, and time, respectively, then     
 

49. 
The dimensions of the slope of a line on a velocity-time graph are _______
 

50. 
The dimensions of the area under the line on an acceleration-time graph are _______
 

51. 
The dimensions of weight are _______
 

52. 
The dimensions of the universal gravitation constant are _______
 

53. 
The dimensions of gravitational field strength are _______
 

54. 
The dimensions of a coefficient of static friction are _______
 

55. 
The dimensions of frequency are _______
 

56. 
The dimensions of the slope of a line on an acceleration-force graph are _______
 

57. 
The law of inertia is also known as _______ .
 

58. 
As the speed of a flowing river increases, the pressure of the flowing water _______ .
 

59. 
An accelerating frame of reference is also known as _______ . In such a frame, we must invent _______  to explain an observed acceleration. If the frame is rotating, the invented force is called _______ .
 

60. 
A passenger of mass m is standing on an elevator that has an acceleration of magnitude a. The normal force acting on the passenger has a magnitude of _______ if the acceleration is upward, and _______ if the acceleration is downward.
 

61. 
On the surface of the Moon, your _______  would be the same as on the surface of Earth, but your _______  would be reduced by a factor of _______ .
 



 
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