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Newton’s Laws Exam Review
Part I: Multiple Choice
1. The law of inertia applies to ___.
a) moving objects.
b) objects at rest.
c) both moving and nonmoving objects.
2. Compared to its weight on earth, a 10-kg object on the moon will weigh ___.
a) less.
b) more.
c) the same amount.
3. Compared to its mass on earth, the mass of a 10-kg object on the moon is ___.
a) less.
b) more.
c) the same.
4.
The mass of a dog that weighs 100 N is about ___.
a) 1 kg
b) 10 kg c) 100 kg
d) 1000 kg
e) none of the above
5.
A 10-N force and a 30-N force act on an object in opposite directions. What is the net force on the object?
a) 40 N
b) 30 N
c) 20 N
d) 10 N
e) none of the above
6.
Which has more mass, a kilogram of feathers or a kilogram of iron?
a) the feathers
b) the iron
c) neither, both have the same mass
7.
How much does a 1 kg bag of nails weigh?
a) 19.6 N
b) 9.8 N c) 7.2 N d) 4.8 N e) 2.4 N
8.
Forces always occur ___.
a) by themselves.
9.
b) as single quantities
c) in pairs
d) in triplets
A student hits a nail with a hammer. During the collision, there is a force ___.
a) on the hammer but not on the nail
b) on the nail but not on the hammer
c) on the nail and also on the hammer
10. A player catches a ball. Consider the action force to be the impact of the ball against the player’s glove. What is the reaction
to this force?
a) the player’s grip on the glove
d) the muscular effort in the player’s arms
b) the force the glove exerts on the ball
e) None of these answers are correct
c) friction of the ground against the player’s shoes
11. The force of friction on a sliding object is 10 N. The applied force needed to maintain a constant velocity is ___.
a) more than 10 N
b) less than 10 N
c) 10 N
12. A hover disc moving with a constant velocity across the floor, will have which one of the following forces acting on it?
a) the force of a push
c) kinetic friction from the floor
b) a normal force
d) the force of gravity
13. A 2 kg block is pulled horizontally with a constant speed across the floor with a force of 10 N. Determine the magnitude of
the frictional force acting on the block.
a) 0 N
b) 5 N
c) 10 N
d) 20 N e) can not be determined
Part II Matching: Match the following terms with the correct definition.
a. gravity
b. mass
c. weight
d. normal force
e. friction
26. Force applied on an object from a surface.
27. Force that always works against the motion that produces it.
28. Product of the object’s mass and gravity.
29. A force that pulls every mass towards the center of the earth.
30. The amount of matter in an object; it determines an object’s inertia.
Diagram
31. The box moves to the left at
constant speed.
Free Body Diagram
32. The box is motionless due to
static friction.
35. A 10 kg box is lowered to the ground with an upward force of 70 N.
FBD:
Summation equation:
Fg:
36. A man pushes a 10 kg lawn mower at a constant velocity. The handle of the lawn mower makes a 40 angle with the ground.
He is pushing on the handle with a force of 50 N.
a) What is the value of the normal force?
b) What is the value of the frictional force opposing motion?
37. A 10 kg box is resting on a 30˚ incline.
a) Draw a free body diagram of the block with components.
b) Calculate the normal force of the block on the incline.
c) Calculate the force of friction acting on the block.
Match the corresponding law. You may use an answer more than once.
a. Newton’s First Law
b. Newton’s Second Law
c. Newton’s Third Law
38.
39.
40.
41
An object in motion will remain in constant motion unless acted on by an unbalanced force.
For every force there is an equal force that is opposite in direction.
A light car with the same engine as a heavier car will accelerate at a greater rate.
A person not wearing a seatbelt will continue to move forward when the car suddenly stops.
True/False
Indicate whether the sentence or statement is true or false. Mark A for TRUE and B for FALSE.
42. A car going along a straight flat road at 60 mph with its cruise control engaged is accelerating.
43.
44.
45.
46.
47.
A motorcycle whose brakes have been applied is accelerating.
A firework at its highest point in the air is accelerating.
Compared to the coefficient of static friction, the coefficient of kinetic friction will always be bigger.
A child sitting on the edge of a merry-go-round which is spinning at a constant speed is accelerating.
A child pushes a toy car to the left and lets it go. The car then slows due to friction. The acceleration of the car is positive.
Assume that the positive direction is to the right.
Multiple Choice
48. A sack of potatoes weighing 200 N falls from an airplane. As the velocity of the fall increases, air resistance also increases.
When air resistance equals 200 N, what is the sack's acceleration?
a. 0 m/s2
b. 4.9 m/s2
c. 9.8 m/s2
d. infinite
49. An object is pulled northward with a force of 10N. A second force pulls southward on the object with a force of 15N. The net
force acting on the object is
a. 25 N northward
b. 25 N southward
c. 5 N northward
d. 5 N southward
50. The force of friction on a sliding object is 10N. The applied force needed to maintain a constant velocity is
a. more than 10N.
b. less than 10 N.
c. 10N.
51. A tow truck exerts a net force of 3000N on a car, accelerating it at 2m/s2. The mass of the car is
a. 500 kg.
b. 1000 kg.
c. 1500 kg.
d. 2000 kg.
Two blocks A and B are connected by means of a string that goes over a pulley. When released, block B pulls block A to the right
(just like in the lab). Assume the friction and air resistance forces to be zero. Assume block B never stops falling.
52. The velocity of block A while on the table
a. is constant for awhile, then increases.
b. continuously increases.
c. continuously decreases.
d. increases for awhile, then remains constant thereafter.
53. If the string were to break when block A was halfway to the edge of the table, the velocity of block B
a. is constant.
b. continuously increases.
c. continuously decreases.
d. increases for awhile, then remains constant thereafter.
e. is constant for awhile, then increases.
54. If the string were to break, when block A reached a point halfway to the egde of the table, the velocity of Block A while it is
on the table
a. is constant.
b. continuously increases
c. continuously decreases.
d. increases for awhile, then remains constant thereafter.
55. A 700. kg compact car can go from rest to a speed of 45 m/s in 9.0s. What average net force acts on the car ?
a. 700 N
b. 3500 N
c. 6860 N
d. 31500 N
Consider the block on a surface below. The coefficient of friction, µ, is 0.20.
56. If a 10. N force is applied to the block, what is its acceleration?
a. 5 m/s2
b. 3.9 m/s2
c. 9.8 m/s2
d.
3.0 m/s2
A 70.0 kg box is pulled across a frictionless surface by a 300. N force at an angle of 30.° to the horizontal.
57. What is the acceleration of the block?
a. 3.7m/s2
b. 3.0 m/s2
c.
2.5 m/s2
d.
9.8 m/s2
58. If the box is pulled at the same angle and same force across a rough table, so that the coefficient of kinetic friction between
the table and box is 0.30, what will be the frictional force acting on the box?
a. 686 N
b. 161 N
c. 150 N
d. 9.8 N
A 20.0 kg block is allowed to accelerate down a 19o ramp with negligible friction.
59. Which of the following is the correct force diagram for the box (no components are included)?
FN
FN
FN
a.
b. FF
c.
d.
FF
FN
FA
Fa
Fg
Fg
Fg
60. Determine the acceleration of the block
a. 3.2 m/s2
b. 4.6 m/s2
c.
9.3 m/s2
61. What is the value of the normal force acting on the block?
a. 9.3 N
b. 20 N
c. 185 N
Fg
d.
9.8 m/s2
d.
196 N
62. Santa lifts a 50 kg bag of presents so that it accelerates upward at 0.5 m/s2. What force did Santa apply to the bag?
a. 25 N
b. 50 N
c. 490 N
d. 515 N
63. A 45 kg wheel barrow is pushed with a force of 200 N at an angle of 45 degrees with the horizontal. The frictional force
opposing the motion is 50 N. The net force acting on the wheel barrow is...
a. 150 N
b. 200 N
c. 141N
d. 91 N