1. Two masses, m1=300 kg and m2=2400 kg, are moving at the same speed. What is the ratio of the kinetic energy of m2 to the kinetic energy of m1?

a. 2:1

*b. 8:1

c. 4:1

d. 9:1

e. 64:1

2. A car at rest at the top of a hill starts rolling down the hill and reaches a speed of 20 m/s at the bottom of the hill. When the car is half way down the hill, what is its speed? Assume that the track is frictionless.

a. 10 m/s

*b. 14.1 m/s

c. 6.3 m/s

d. 20 m/s

e. none of them

3. If a 70 kg man runs up stairs that rise vertically 5.0 m in 5.2 s. What is the power supplied by his muscles?

a. 3434 W

b. 32.4 W

c. 330 W

*d. 660 W

4. A 2 kg object is dropped from a height of 11.0 m. What is its kinetic energy just before the object hits the ground?

a. 22.0 J

b. 0.98 J

*c. 215.8 J

d. 31.6 J

5. If the power capability of a motor is increased, then it:

a. has a requirement for longer time intervals for doing the work

b. can only do the same amount of work in a shorter time interval

*c. has a greater ability to do the work

d. has a shorter workload

6. When a 2.55 kg falling ball is 0.50 m above the floor, its potential energy exactly equals its kinetic energy. How fast is it moving at this moment?

*a. 3.1 m/s

b. 9.8 m/s

c. 10.1 m/s

d. 45 m/s

7. The swing of a pendulum reaches a height of 1.0 m above its lowest position. What is its speed at its lowest position?

*a. 4.43 ms^-1

b. 9.81 ms^-1

c. 19.6 ms^-1

d. 44.3 ms^-1

e. none of these

8. Two masses are released from the top of a tower. One slides down a frictionless ramp and the other falls straight down. Which one is moving faster when it reaches the bottom?

a. The mass that went straight down

b. The mass that slid down the ramp

*c. They both will have the same speed

d. This problem is missing information

9. A high jumper clears a 2.50 m bar. What is his velocity just before landing?

a. 2.65 m/s

b. 5.40 m/s

*c. 7.00 m/s

d. 49.1 m/s

10. If a 1500 kg sports car accelerates from 0 to 25 m/s in 5.0 seconds, how much power must go into accelerating the car?

*a. 93,750 W

b. 7500 W

c. 468,800 W

d. 46,875 W

11. A gun fires a 10 kg projectile at an angle of 25^oabove the horizontal. The projectile’s initial velocity is 250 m/s and its final velocity is 200 m/s. What is the change in the internal energy of the projectile?

a. +12,500 J

b. -12,500 J

c. +112,500 J

*d. -112,500 J

e. 0

12. The mechanical energy of a system of objects is conserved:

*a. there is no friction and all collisions are elastic and the work done by the resultant external force is zero

b. only when the objects move along open paths

c. always

d. none of the above

13. A gun fires a 1 kg projectile is fired at an angle of 60^oabove the horizontal with an initial speed of 20 m/s. Its potential energy of the projectile at the highest point of its path is:

a. 25 J

b. 75 J

*c. 150 J

d. 300 J

e. none of these