1) A total of 4900 J is expended in lifting a 50-kg mass. The mass is raised to a height of
a) 10 m.
b) 98 m.
c) 960 m.
d) 245, 000 m.
2) In a good wind, a modern large wind turbine might have a power output of
a) 2 kW.
b) 20 kW.
c)200 kW.
d)2000 kW.
3) It seems possible that a serious effort to improve the efficiency of electricity use in the United States could reduce its consumption of electric energy by
a) 5 %
b) 10 %
c) 25%
d) 50 %
4) Which of the following statements is incorrect?
a) all vector quantities have directions.
b) all vector quantities have magnitudes.
c) all scalar quantities have directions.
d) all scalar quantities have magnitudes.
5) A car starts from a speed of 10 m/s with an acceleration of 2 m/s^2. The time needed for the car to reach 30 m/s is
a) 10 s.
b) 20 s.
c) 30 s.
d) 40 s.
6) An airplane travels at a constant speed for a distance of 120 km in a time of 15 minutes. Its speed is
a) 30 km/h
b) 120 km/h
c) 480 km/h
d) 1800 km/h
7) Which of the following statements is not true?
a) Coal-fired power plants in the United States produce over half of its electricity.
b) About 150 new coal-fired power plants are newly built or under construction in the United States.
c) The United States has less than 5 percent of the world's coal reserves.
d) Coal is cheaper per unit of energy released when it is burned than any other fossil fuel.
8) In 6 minutes, a person running 10 km/h covers a distance of
a) 167 m.
b) 600 m.
c) 1000 m.
d) 1667 m.
9) A 1-N weight has a PE relative to the ground of 1 J when it is at a height of
a) 10.2 cm.
b) 1 m.
c) 9.8 m.
d) 98 m.
10) If the Anatarctic and Greenland icecaps melt completely, sea level will rise
a) mainly in the tropical regions.
b) mainly in the polar regions.
c) everywhere by about 1 m.
d) everywhere by about 10 m.
11) In bright sunlight, a solar cell with an efficiency of 20% might have a power output per square meter of
a) 2 w.
b) 20 w.
c) 200 w.
d) 2000 w.
12) A square foor contains approximately
a) 144 cm^2
b) 366 cm^2
c) 929 cm^2
d) 1000 cm^2
13) An 800-kg car moving at 80 km/h collides head-on with a 1200-kg car moving at 40 km/h in the opposite direction. The total kinetic energy lost by the car is
a) 0.
b) less than lost by the cars in question 48.
c) the same as that lost by the cars in question 48
d) more than that lost by the cars in question 48.
14) In the past century the world's polulation has increased by about
a) 10 percent
b) 50 percent
c) 100 percent
d) 300 percent
15) A horse has a power output of 1 hp(746 W) when it is pulling a cart. If the cart covers 100 m in 30 s, the force the horse exerts on the cart is
a) 0.22 kN.
b) 0.34 kN.
C0 0.45 kN
d) 2.49 kN.
16) A golf ball and a ping-pong ball are dropped in a vacuum chanber. When they have fallen halfway down, they have the same
a) speed
b) potential energy
c) kinetic energy
d) rest energy
17) Methane is the chief constituent of
a) natural gas
b) gasoline
c) diesel fuel
d) ethanol
18) Environmental concerns are the most important factor in limiting the expansion of which of the following energy sources?
a) wind
b) geothermal
c) hydropower
d) solar
19) When a planet is farthest from the sun in its orbit,
a) its speed is greatest.
b) its speed is the same as when it is farther away.
c) its speed is least.
d) Any of the choices, depending on which planet it is.
20) The proportion of the world's electricity that comes from nuclear energy is about
a) 1/20.
b) 1/6.
c) 1/3.
d) 1/2