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8. Two cars have the same mass, but one is moving three times as
KEY TERMS
fast as the other is. How much more work will be needed to stop
the faster car?
chemical energy (p. 70)

a. The same amount.
electrical energy (p. 71) b. Twice as much.
energy (p. 67) c. Three times as much.

fossil fuels (p. 76) d. Nine times as much.
geothermal energy (p. 79) 9. Kinetic energy can be measured in terms of
horsepower (p. 65) a. work done on an object to put it into motion.
joule (p. 62) b. work done on a moving object to bring it to rest.
kinetic energy (p. 68) c. both a and b.
law of conservation of energy (p. 74) d. neither a nor b.
mechanical energy (p. 70) 10. Potential energy and kinetic energy are created when work
nuclear energy (p. 71) is done to change a position (PE) or a state of motion (KE).
potential energy (p. 67) Ignoring friction, how does the amount of work done to make
power (p. 65) the change compare to the amount of PE or KE created?
radiant energy (p. 71) a. Less energy is created.
b. Both are the same.
watt (p. 66)
c. More energy is created.
work (p. 62)
d. This cannot be generalized.

11. Many forms of energy in use today can be traced back to
APPLYING THE CONCEPTS a. the Sun.
b. coal.
c. Texas.

1. According to the definition of mechanical work, pushing on a d. petroleum.
rock accomplishes no work unless there is
a. movement. 12. In all of our energy uses, we fi nd that
b. a net force. a. the energy used is consumed.
c. an opposing force. b. some forms of energy are consumed but not others.
d. movement in the same direction as the direction of the force. c. more energy is created than is consumed.
d. the total amount of energy is constant in all situations.
2. The metric unit of a joule (J) is a unit of

a. potential energy. 13. Any form of energy can be converted to another, but energy used
b. work. on Earth usually ends up in what form?
c. kinetic energy. a. Electrical
d. any of the above. b. Mechanical
c. Nuclear
3. A Nm/s is a unit of d. Radiant
a. work.
b. power. 14. Radiant energy can be converted to electrical energy using
c. energy. a. lightbulbs.
d. none of the above. b. engines.
c. solar cells.
4. A kilowatt-hour is a unit of d. electricity.
a. power.

b. work. 15. The “barrel of oil” mentioned in discussions about
c. time. petroleum is
d. electrical charge. a. 55 U.S. gallons.
b. 42 U.S. gallons.

5. A power rating of 550 ft · lb per s is known as a c. 12 U.S. gallons.
a. watt. d. a variable quantity.
b. newton.

c. joule. 16. The amount of energy generated by hydroelectric plants in the
d. horsepower. United States as part of the total electrical energy is
a. fairly constant over the years.
6. A power rating of 1 joule per s is known as a b. decreasing because new dams are not being constructed.
a. watt. c. increasing as more and more energy is needed.
b. newton. d. decreasing as dams are destroyed because of environmental
c. joule. concerns.
d. horsepower.
17. Fossil fuels provide what percent of the total energy consumed in
7. According to PE = mgh, gravitational potential energy is the the United States today?
same thing as a. 25 percent
a. exerting a force through a distance in any direction. b. 50 percent
b. the kinetic energy an object had before coming to a rest. c. 86 percent
c. work against a vertical change of position. d. 99 percent
d. the momentum of a falling object.

3-21 CHAPTER 3 Energy 81