Practice Quiz 5 Energy

Practice Quiz 5
1) The work done by the centripetal force on an object with a mass of 1 kg moving with a constant velocity of 4 m/s into a circular path of radius 0.6 m for one full cycle is
A) 100.7 J
B) 3.8 J
C) 0 J
D) 80 J
Answer: C

2) An object of mass 10.0 kg is initially at rest. A 100 N force causes it to move horizontally through a distance of 6.00 m. What is the change in the kinetic energy of this object?
A) 0 J
B) 200 J
C) 60.0 J
D) 600 J
Answer: D

3) A boy throws a ball to another boy who throws it back with half the original speed. What is the ratio of the final kinetic energy to the initial kinetic energy of the ball?
A) 0.25
B) 0.50
C) 2.00
D) 0.75
Answer: A

4) An object of mass 4 kg is thrown vertically upwards from ground level with an initial speed of 20 m/s. Ignore friction and use g = 10 m/s2. What is the kinetic energy of the object just before it hits the ground?
A) 800 J
B) 0 J
C) 100 J
D) 200 J
Answer: A

5) 4.0 J of work are performed in stretching a spring with a spring constant of 2500 N/m. How much is the spring stretched?
A) 3.2 cm
B) 0.3 cm
C) 5.7 m
D) 5.7 cm
Answer: D

6) A weight of 200 N is hung from a spring with a spring constant of 2500 N/m and lowered slowly. How much will the spring stretch?
A) 4.00 cm
B) 6.00 cm
C) 8.00 cm
D) 10.0 cm
Answer: C

7) If the work done to stretch a spring by 4.0 cm is 6.0 J, what is the spring constant?
A) 300 N/m
B) 3000 N/m
C) 7500 N/m
D) 6000 N/m
Answer: C

8) A truck has four times the mass of a car and is moving with twice the speed of the car. If Kt and Kc refer
to the kinetic energies of truck and car respectively, it is correct to say that
A) Kt = 16 Kc.
B) Kt = 4 Kc.
C) Kt = Kc.
D) Kt =
2
1 Kc.
Answer: A

9) An object is under the influence of a force as represented by the force vs. position graph in Figure. What
is the work done as the object moves from 6 m to 12 m?
A) 20 J
B) 30 J
C) 0 J
D) 40 J
Answer: B

10) A person applies a constant force on an object of mass 20 kg that causes the object to move
horizontally at a constant speed of 0.20 m/s through a distance of 0.80 m. What is the work done on the
object?
A) 10 J
B) 16 J
C) 0 J
D) None of the other choices is correct.
Answer: C