Physics: Principles with Applications, Sixth Edition
35) A packing crate slides down an inclined ramp at constant velocity. Thus we can deduce that
A) a frictional force is acting on it.
B) a net downward force is acting on it.
C) it may be accelerating.
D) it is not acted on by appreciable gravitational force.
Answer: A
Diff: 1 Page Ref: Sec. 4.8
36) A block of mass M slides down a frictionless plane inclined at an angle q with the horizontal.
The normal reaction force exerted by the plane on the block is
A) Mg.
B) Mg sin q.
C) Mg cos q.
D) zero, since the plane is frictionless.
Answer: C
Diff: 1 Page Ref: Sec. 4.8
37) A block of mass M slides down a frictionless plane inclined at an angle q with the horizontal.
The normal reaction force exerted by the plane on the block is directed
A) parallel to the plane in the same direction as the movement of the block.
B) parallel to the plane in the opposite direction as the movement of the block
C) perpendicular to the plane.
D) toward the center of the Earth.
Answer: C
Diff: 1 Page Ref: Sec. 4.8
38) A block of mass M slides down a frictionless plane inclined at an angle q with the horizontal.
The gravitational force is directed
A) parallel to the plane in the same direction as the movement of the block.
B) parallel to the plane in the opposite direction as the movement of the block
C) perpendicular to the plane.
D) toward the center of the Earth.
Answer: D
Diff: 1 Page Ref: Sec. 4.8
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, Chapter 4: Dynamics: Newton's Laws of Motion
39) Two toy cars (16 kg and 2.0 kg) are released simultaneously on an inclined plane that makes an
angle of 30e with the horizontal. Make a statement which best describes their acceleration after
being released.
A) The 16-kg car accelerates 8 times faster than the 2.0-kg car.
B) The 2.0-kg car accelerates 8 times faster than the 16-kg car.
C) Both cars accelerate at the same rate.
D) none of the above
Answer: C
Diff: 2 Page Ref: Sec. 4.8
Quantitative Problems
1) An object sits on a frictionless surface. A 16-N force is applied to the object, and it accelerates
at 2.0 m/s2. What is the mass of the object?
A) 4.0 kg
B) 8.0 kg
C) 32 kg
D) 78 N
Answer: B
Diff: 1 Page Ref: Sec. 4.4-4.6
2) A sports car of mass 1000 kg can accelerate from rest to 27 m/s in 7.0 s. What is the average
forward force on the car?
A) 2.6 ˛ 102 N
B) 3.9 ˛ 103 N
C) 2.7 ˛ 104 N
D) 1.9 ˛ 105 N
Answer: B
Diff: 1 Page Ref: Sec. 4.4-4.6
3) Starting from rest, a 4.0-kg body reaches a speed of 8.0 m/s in 2.0 s. What is the net force
acting on the body?
A) 4.0 N
B) 8.0 N
C) 16 N
D) 32 N
Answer: C
Diff: 2 Page Ref: Sec. 4.4-4.6
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35) A packing crate slides down an inclined ramp at constant velocity. Thus we can deduce that
A) a frictional force is acting on it.
B) a net downward force is acting on it.
C) it may be accelerating.
D) it is not acted on by appreciable gravitational force.
Answer: A
Diff: 1 Page Ref: Sec. 4.8
36) A block of mass M slides down a frictionless plane inclined at an angle q with the horizontal.
The normal reaction force exerted by the plane on the block is
A) Mg.
B) Mg sin q.
C) Mg cos q.
D) zero, since the plane is frictionless.
Answer: C
Diff: 1 Page Ref: Sec. 4.8
37) A block of mass M slides down a frictionless plane inclined at an angle q with the horizontal.
The normal reaction force exerted by the plane on the block is directed
A) parallel to the plane in the same direction as the movement of the block.
B) parallel to the plane in the opposite direction as the movement of the block
C) perpendicular to the plane.
D) toward the center of the Earth.
Answer: C
Diff: 1 Page Ref: Sec. 4.8
38) A block of mass M slides down a frictionless plane inclined at an angle q with the horizontal.
The gravitational force is directed
A) parallel to the plane in the same direction as the movement of the block.
B) parallel to the plane in the opposite direction as the movement of the block
C) perpendicular to the plane.
D) toward the center of the Earth.
Answer: D
Diff: 1 Page Ref: Sec. 4.8
67
, Chapter 4: Dynamics: Newton's Laws of Motion
39) Two toy cars (16 kg and 2.0 kg) are released simultaneously on an inclined plane that makes an
angle of 30e with the horizontal. Make a statement which best describes their acceleration after
being released.
A) The 16-kg car accelerates 8 times faster than the 2.0-kg car.
B) The 2.0-kg car accelerates 8 times faster than the 16-kg car.
C) Both cars accelerate at the same rate.
D) none of the above
Answer: C
Diff: 2 Page Ref: Sec. 4.8
Quantitative Problems
1) An object sits on a frictionless surface. A 16-N force is applied to the object, and it accelerates
at 2.0 m/s2. What is the mass of the object?
A) 4.0 kg
B) 8.0 kg
C) 32 kg
D) 78 N
Answer: B
Diff: 1 Page Ref: Sec. 4.4-4.6
2) A sports car of mass 1000 kg can accelerate from rest to 27 m/s in 7.0 s. What is the average
forward force on the car?
A) 2.6 ˛ 102 N
B) 3.9 ˛ 103 N
C) 2.7 ˛ 104 N
D) 1.9 ˛ 105 N
Answer: B
Diff: 1 Page Ref: Sec. 4.4-4.6
3) Starting from rest, a 4.0-kg body reaches a speed of 8.0 m/s in 2.0 s. What is the net force
acting on the body?
A) 4.0 N
B) 8.0 N
C) 16 N
D) 32 N
Answer: C
Diff: 2 Page Ref: Sec. 4.4-4.6
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