Physics: Principle and Applications, 7e (Giancoli)
Chapter 4 Dynamics: Newton's Laws of Motion
4.2 Problems
1) What is the mass of an object that experiences a gravitational force of 685 N near Earth's
surface where g = 9.80 m/s2?
A) 69.9 kg
B) 68.5 kg
C) 71.3 kg
D) 72.7 kg
Answer: A
Var: 50+
9) A 40-kg crate is being lowered with a downward acceleration is 2.0 m/s2 by means of a rope.
(a) What is the magnitude of the force exerted by the rope on the crate?
(b) What would be the magnitude of the force exerted by the rope if the crate were being raised
with an acceleration of 2.0 m/s2?
Answer: (a) 310 N (b) 470 N
Var: 1
13) A certain aircraft has a mass of 300,000 kg. At a certain instant during its landing, its speed
is 27.0 m/s. If the braking force is a constant 445,000 N, what is the speed of the airplane 10.0 s
later?
A) 10.0 m/s
B) 12.2 m/s
C) 14.0 m/s
D) 18.0 m/s
E) 20.0 m/s
Answer: B
Var: 5
1
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21) A box of mass 72 kg is at rest on a horizontal frictionless surface. A constant horizontal force
of magnitude F then acts on the box, accelerating it to the right. You observe that it takes the box
3.4 seconds to travel 13 meters. What is the magnitude of the force F?
Answer: 160 N
Var: 50+
27) The figure shows an acceleration-versus-force graph for a 125-g object. What should be the
value of the first tick-mark on the vertical scale, as indicated by the arrow in the figure?
A) 4
B) 8
C) 0.00400
D) 0.00800
Answer: A
Var: 12
2
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29) The figure shows an acceleration-versus-force graph for three objects pulled by wires. If the
mass of object 2 is 36 kg, what are the masses of objects 1 and 3?
A) 12 kg and 90 kg
B) 72 kg and 18 kg
C) 90 kg and 12 kg
D) 12 kg and 72 kg
Answer: A
Var: 1
35) A 30.0-kg load is being held in place using massless wires in the ideal pulley arrangement
shown in the figure. What is the magnitude of the force F?
Answer: 147 N
Var: 1
3
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58) The figure shows a 100-kg block being released from rest from a height of 1.0 m. It then
takes 0.53 s for it to reach the floor. What is the mass m of the block on the left? There is no
friction or mass in the pulley, and the connecting rope is very light.
A) 16 kg
B) 14 kg
C) 13 kg
D) 11 kg
Answer: A
Var: 50
4
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60) In the figure, block A has a mass of 3.00 kg. It rests on a smooth horizontal table and is
connected by a very light horizontal string over an ideal pulley to block B, which has a mass of
2.00 kg. When block B is gently released from rest, how long does it take block B to travel 80.0
cm?
A) 0.404 s
B) 0.494 s
C) 0.639 s
D) 0.785 s
E) 0.935 s
Answer: C
Var: 5
5
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