Chapter 5 – Work and Energy – Review Questions
1. In pulling a chest of drawers, a force of 60.0N is applied at an angle of 60.0°. How much work
is done in pulling it over a distance of 10.0 m?
2. How much work is done when a car is pushed 10.0 m by a force of 800 N?
3. You’re travelling in a car at 88 m/s. If your mass is 80.0 kg, and the car has a mass of 1200 kg,
what is the total kinetic energy of the car and you combined?
4. A force of 600.0 N is applied to a 1000-kg car. Under the influence of this force, it travels a
distance of 100 m on a frictionless, icy road. What is the car’s speed at the end of the 100 m?
5. A force of 6000 N is applied to a hockey puck with a mass of 0.10 kg. It travels over a
distance of 0.10 m on a frictionless ice rink. What is the puck’s final speed?
6. A 40-kg box of books falls off a shelf that is 4.0 m above the ground. How fast is the box
travelling when it hits the ground?
7. The flagpole on a 300.0-m skyscraper falls off. How fast is it falling when it strikes the
ground?
8. How far must you stretch a spring with k = 1000 N/m to store 200 J of energy?
9. How much energy can be stored in a spring with a spring constant of 500 N/m if its maximum
possible stretch is 20 cm?
10. In a wild shot, Jimmy flings a pool ball off a 0.68-m-high pool table, and the ball hits the
floor with a speed of 6.00 m/s. How fast was the ball moving when it left the pool table?
11. Brittany is changing the tire of her car on a steep hill 20.0 m high. She trips and drops the
10.0-kg spare tire, which rolls down the hill with an initial speed of 2.00 m/s. What is the
speed of the tire when it reaches the top of the next hill, which is 5.00 m high? (Ignore the
effects of friction.)
12. A 1000-kg car accelerates from 88 m/s to 100 m/s in 30 s. How much power does that
require?
13. You’re driving a snowmobile that accelerates from 10 m/s to 20 m/s over a time interval of
10.0 s. If you and the snowmobile together have a mass of 500 kg, how much power is used?
14. Clyde, a stubborn 3500-N mule, refuses to walk into the barn, so Farmer MacDonald must
drag him up a 5.0-m-long ramp to his stall, which stands 0.50 m above ground level. (a) If
Farmer MacDonald needs to exert a 450-N force on the mule to drag him up the ramp with a
constant speed, what is the mechanical advantage of the ramp? (b) What is the efficiency of
the ramp?
15. A pulley system lifts a 1345-N weight a distance of 0.975 m. The person using the system
pulls the rope a distance of 3.90 m, exerting a force of 375 N. (a) What is the mechanical
advantage of the system? (b) How efficient is the system?
Know:
• Definition of work, energy, kinetic energy, potential energy, power
• Types of potential energy
• Work-Kinetic Energy Theorem
• Conservation of mechanical energy
• Simple Machines starts on pg. 258
1. W = 300 J
2. W = 8000 J
3. KE = 4.9 × 106 J
4. vf = 11 m/s
5. vf = 110 m/s
6. v2 = 8.8 m/s
7. 77 m/s
8. x = 0.63 m
9. PEe = 10 J
10. v1 = 4.8 m/s
11. v2 = 17.3 m/s
12. 3.8 × 104 W
13. P = 7500 W
14. MA = 7.8
eff = 78%
15. MA = 3.56
eff = 90.0%