Download Newton Laws (Extra problems for practice) 1) To determine the mass

Newton Laws (Extra problems for practice)
1) To determine the mass of a car, a student (with a friend at the wheel) pushes the car holding a bathroom scale
between himself and the car and carefully maintains a constant reading of 400 N on the scale while the car
accelerates on level ground. At the conclusion of the experiment his friend reports that the car accelerated from rest
to 14.0 km/hr in 12.0 s. What was the mass of the car?
A) 343 kg
B) 1230 kg
C) 3360 kg
D) 3430 kg
Answer: B
2) Three boxes rest side-by-side on a smooth, horizontal floor. Their masses are 5.0 kg, 3.0 kg, and 2.0 kg, with the
3.0-kg mass in the center. A force of 50 N pushes on the 5.0-kg mass, which pushes against the other two masses.
What is the contact force between the 5.0-kg mass and the 3.0-kg mass?
A) 0 N
B) 10 N
C) 25 N
D) 40 N
Answer: C
3) Three boxes rest side-by-side on a smooth, horizontal floor. Their masses are 5.0 kg, 3.0 kg, and 2.0 kg, with the
3.0-kg mass in the center. A force of 50 N pushes on the 2.0-kg mass, which pushes against the other two masses.
What is the contact force between the 5.0-kg mass and the 3.0-kg mass?
A) 0 N
B) 10 N
C) 25 N
D) 40 N
Answer: C
4) A locomotive is pulling three wagons along a level track with a force of 100,000 N. The wagon next to the
locomotive has a mass of 80,000 kg, the next one, 50,000 kg, and the last one, 70,000 kg. Neglect friction. What is
the force between the 80,000-kg and 50,000-kg wagons?
A) 35,000 N
B) 40,000 N
C) 60,000 N
D) 65,000 N
Answer: C
5) A locomotive is pulling three wagons along a level track with a force of 100,000 N. The wagon next to the
locomotive has a mass of 70,000 kg, the next one, 50,000 kg, and the last one, 80,000 kg. Neglect friction. What is
the force between the 80,000-kg and 50,000-kg wagons?
A) 35,000 N
B) 40,000 N
C) 60,000 N
D) 65,000 N
Answer: B
6) A 50.0-kg crate is being pulled along a horizontal, smooth surface. The pulling force is 10.0 N and is directed
20.0° above the horizontal. What is the acceleration of the crate?
A) 0.0684 m/s2
B) 0.188 m/s2
C) 0.200 m/s2
D) 0.0728 m/s2
Answer: B
7) A 40.0-kg box is being pushed along a horizontal, smooth surface. The pushing force is 15.0 N directed at an
Walker – Chapter 5 RTF – p. 1
angle of 15.0° below the horizontal. What is the acceleration of the crate?
A) 0.158 m/s2
B) 0.362 m/s2
C) 0.466 m/s2
D) 0.375 m/s2
Answer: B
8) A 1000-kg barge is being towed by means of two horizontal cables. One cable is pulling with a force of 80.0 N in
a direction 30.0° west of north. The second cable pulls in a direction 20.0° east of north. What should the magnitude
of its pulling force be so that the barge will accelerate northward?
A) 127 N
B) 120 N
C) 117 N
D) 73.7 N
Answer: C
9) An object is being acted upon by three forces and moves with a constant velocity. One force is 60.0 N along the
x-axis, the second is 75.0 N along the y-axis. What is the magnitude of the third force?
A) 135 N
B) 15.0 N
C) 48.0 N
D) 96.0 N
Answer: D
10) An object is being acted upon by three forces and moves with a constant velocity. One force is 60 N along the
x-axis, the second is 75 N along the y-axis. What is the direction of the third force, measured counterclockwise from
the x-axis?
A) 128°
B) 182°
C) 213°
D) 231°
Answer: D
11) An object is being acted upon by three forces and moves with a constant velocity. One force is 60 N along the
x-axis, the second is 75 N along a direction making a counterclockwise angle of 150° with the x-axis. What is the
direction of the third force, measured counterclockwise from the x axis?
A) 128°
B) 182°
C) 226°
D) 262°
Answer: D
12) An object is being acted upon by three forces and moves with a constant velocity. One force is 60 N along the
x-axis, the second is 75 N along a direction making a clockwise angle of 150° with the x-axis. What is the direction
of the third force, measured clockwise from the x-axis?
A) 164°
B) 146°
C) 236°
D) 262°
Answer: D
13) A 400-kg box is lifted vertically upward with constant velocity by means of two cables pulling at 35.0° on
either side of the vertical direction. What is the tension in each cable?
A) 231 N
B) 400 N
C) 2390 N
Walker – Chapter 5 RTF – p. 2
D) 3920 N
Answer: C
14) A 10.0-kg picture is held in place by two wires, one hanging at 45.0° to the left of the vertical and the other at
45.0° to the right of the vertical. What is the tension in the second wire?
A) 71.8 N
B) 69.4 N
C) 98.1 N
D) 50.8 N
Answer: B
Walker – Chapter 5 RTF – p. 3