Ch 08 Work and Power SAMPLE QUESTIONS
Multiple Choice
Identify the choice that best completes the statement or answers the question.
1. Work may be measured using units of:
A. / watts.B. / newtons.
C. / newtons per second.
D. / joules.
2. When a force applied to an object causes the object to move in the direction of the force, the object acquires:
A. / efficiency.B. / friction.
C. / energy.
D. / mechanical advantage.
3. The work output of a machine:
A. / must be equal to the work input.B. / is always changing the work input.
C. / is always less than the work input.
D. / is always greater than the work input.
4. The efficiency of a machine is usually expressed in:
A. / percent.B. / joules.
C. / watts.
D. / newton-meters.
5. Which of the following use the same units of measurement?
A. / Power and energyB. / Energy and work
C. / Force and work
D. / Power and work
6. A gallon of gasoline contains chemical energy. If you pour a gallon of gasoline into your car, you could drive for about 20 miles on the highway (about 20 minutes). You could choose instead to run a lawn mower for an hour with one gallon of gasoline. If the gasoline were to come in contact with a fire, the entire gallon would burn in less than a minute. Which reaction has the most power?
A. / They are equal because the gasoline has the same chemical potential energy in each case.B. / Burning the gasoline in the car
C. / Burning the gasoline in a fire
D. / Burning the gasoline in the lawn mower
7. Which of the following improves the efficiency of a machine?
A. / Running it fasterB. / Adding more energy
C. / Increasing friction
D. / Reducing friction
8. The measure of how effective a machine is in using energy to do work is called:
A. / transformation.B. / mechanical advantage.
C. / work output.
D. / efficiency.
9. The equation used to calculate work when force is applied to move an object some distance is:
A. / Work = force ´ distanceB. / Work = force ÷ distance
C. / Work = force + distance
D. / Work = distance ÷ force
10. The action that would require NO work to be done is:
A. / holding a 100-pound object over your head.B. / pedaling a 100-newton bicycle up a small hill.
C. / lifting a balloon filled with air from the floor to a desktop.
D. / pushing a 25-kilogram box of books across the floor.
11. A 60-newton block at rest at the bottom of a frictionless incline plane is pushed up the incline:
The amount of work done against gravity is ____ joules.
A. / 0B. / 20
C. / 60
D. / 180
12. A unit used to measure power is the:
A. / joule.B. / newton-meter.
C. / watt.
D. / newtons per second.
13. A system of pulleys is used to lift an elevator carrying a 3,300-newton load. Assuming the pulley system is nearly friction-free, approximately how far would 10,000 joules of energy lift the elevator?
A. / 0.3 metersB. / 3 meters
C. / 30 meters
D. / 300 meters
14. Efficiency is defined as the ratio of:
A. / input force to output force.B. / work input to the work output.
C. / output force to input force.
D. / work output to work input.
15. What is the most work that can be done with 200 joules of energy?
A. / 20,000 JB. / 2,000 J
C. / 20 J
D. / 200 J
16. If forces A, B and C are equal, the work done by the forces as they are exerted on the box is:
A. / greatest for force A.B. / greatest for force B.
C. / greatest for force C.
D. / the same for all forces.
Ch 08 Work and Power SAMPLE QUESTIONS
Answer Section
MULTIPLE CHOICE
1. ANS: D
2. ANS: C
3. ANS: C
4. ANS: A
5. ANS: B
6. ANS: C
7. ANS: D
8. ANS: D
9. ANS: A
10. ANS: A
11. ANS: D
12. ANS: C
13. ANS: B
14. ANS: D
15. ANS: D
16. ANS: C