Physics Chapter 5

If the radius of Earth decreased, with no change in mass, your weight would _____. a. increase b. not change c. decrease

A

Jupiter has more than 300 times the mass of Earth. Yet on Jupiter's surface an object weighs only about 3 times as much as it would on Earth. The explanation to this involves Jupiter's _____. a. large radius b. high density c. greater distance from the sun

A

Suppose the gravitational force between two masses is 70 N. If the magnitude of one of the masses halves, what is the force between the masses? a. 35 N b. 18 N c. 280 N d. 70 N e. 140 N

A

Suppose the gravitational force between two massive spheres is 100 N. If the distance between the spheres is doubled, what is the force between the masses? a. 25 N b. 400 N c. 200 N d. 50 N e. 100 N

A

Suppose the gravitational force between two spheres is 30 N. If the magnitude of each mass doubles, what is the force between the masses? a. 120 N b. 60 N c. 8 N d. 15 N e. 30 N

A

A race car traveling at a constant speed of 50 m/s drives around a circular track that is 250 m in radius. What is the magnitude of the acceleration of the car? a. 10 m/s2 b. 2.2 m/s2 c. 0 m/s2 d. 1.0 m/s2 e. 0.63 m/s2

A

The force of gravity on you is greatest when you are standing _____. a. on Earth's surface b. just above Earth's surface c. far above Earth's surface

A

The speed of a satellite in an elliptical orbit is _____. a. not constant b. independent of the height of the satellite c. constant

A

Two objects move toward each other because of gravitational attraction. As the objects get closer and closer, the force between them _____. a. increases b. decreases c. remains constant

A

When an object moves in uniform circular motion, the direction of its acceleration is a. is directed toward the center of its circular path. b. in the opposite direction of its velocity vector. c. in the same direction as its velocity vector. d. depends on the speed of the object. e. is directed away from the center of its circular path.

A

Where does a satellite in an elliptical orbit have the greatest kinetic energy? a. At the point closest to the planet b. Exactly at the point halfway to the planet c. At the point farthest from the planet d. Anywhere -- its kinetic energy is constant e. More information is needed

A

Which is greater, the gravitational force between Earth and the moon, or the force between Earth and the sun? a. Earth-sun b. Earth-moon c. equal

A

A car goes around a circular curve on a horizontal road at constant speed. What is the direction of the friction force on the car due to the road? a. tangent to the curve in the forward direction b. perpendicular to the curve inward c. tangent to the curve opposite to the direction of the car's motion d. perpendicular to the curve outward e. There is no friction on the car because its speed is constant.

B

A very massive object A and a less massive object B move toward each other under the influence of mutual gravitation. Which force, if either, is greater? a. The force on B b. Both forces are the same. c. The force on A

B

If Earth rotated more slowly about its axis, your weight would a. decrease. b. increase. c. stay the same.

B

If Earth's mass decreased to one half its original mass, with no change in radius, then your weight would _____. a. stay the same b. decrease to one half your original weight c. decrease to one quarter your original weight d. none of the above

B

Since Earth is attracted to the sun, why doesn't it fall into the sun? a. Because it has too much mass to move toward the sun b. Because it has sufficient tangential velocityere is an equal force holding it away from the sun d. Because it has too much inertia to move toward the sun e. all of the above

B

The force of gravity does work on a satellite when it is in _____. a. circular orbit b. elliptical orbit c. both A and B d. neither A nor B

B

The reason the moon does not fall into Earth is that _____. a. Earth's gravitational field at the moon is weak b. the moon has a sufficiently large orbital speed c. gravitational pull of other planets keeps the moon up d. the moon has less mass than Earth e. none of the above

B

To weigh less in the Northern Hemisphere, you should go a. east. b. south. c. north. d. west.

B

Suppose the gravitational force between two spheres is 70 N. If the distance between the spheres is halved, what is the force between the masses? a. 70 N b. 35 N c. 280 N d. 140 N e. 17.5 N

B?

A 0.50-kg toy is attached to the end of a 1.0-m very light string. The toy is whirled in a horizontal circular path on a frictionless tabletop. If the maximum tension that the string can withstand without breaking is 350 N. What is the maximum speed the mass can have without breaking the string? a. 13 m/s b. 19 m/s c. 26 m/s d. 700 m/s

C

A car travels in a circle with constant speed. The net force on the car a. is zero because the car is not accelerating. b. is directed forward, in the direction of travel. c. is directed toward the center of the curve. d. none of the above

C

A planet has half the mass of the Earth and half the radius. Compared to its weight on Earth, an apple on this planet would weigh _____. a. one-fourth as much b. half as much c. twice as much d. the same e. zero

C

A supplier wants to make a profit by buying metal by weight at one altitude and selling it at the same price per pound at another altitude. The supplier should _____. a. disregard altitude because it has a negligible effect b. buy at a high altitude and sell at a low altitude c. buy at a low altitude and sell at a high altitude

C

An object is placed exactly halfway between Earth and the moon. The object will fall toward _____. a. the moon b. neither Earth nor the moon c. Earth

C

As a satellite is moving in orbit around the Earth, the sum of the kinetic energy and potential energy everywhere is _______ a. zero. b. decreasing. c. constant. d. increasing.

C

If the mass of Earth increased, with no change in radius, your weight would _____. a. stay the same b. decrease c. increase also

C

If you whirl a tin can on the end of a string and the string suddenly breaks, the can will a. fly directly away from you. b. spiral away from your hand. c. fly off, tangent to its circular path. d. fly directly toward you. e. spiral in toward your hand.

C

The centripetal force exerted on stunt motorcyclist Biker Bob while riding on the inner vertical surface of a circular track is a. friction. b. his weight. c. the normal force. d. none of the above

C

The speed of a satellite in a circular orbit is _____. a. constantly increasing b. not constant c. constant

C

What is the direction of the force that acts on clothes in the spin cycle of a washing machine? a. Outward b. Down c. Inward d. Up

C

When a car goes around a circular curve on a horizontal road at constant speed, what force causes it to follow the circular path? a. the normal force from the road b. gravity c. the friction force from the road d. No force causes the car to do this because the car is traveling at constant speed and therefore has no acceleration.

C

A person weighs less at the equator than at the poles. The reason for this has to do with the a. tidal bulges. b. influence of the sun, moon, and all the planets. c. higher temperature at the equator, and expansion of matter. d. spin of the Earth. e. none of the above

D

A tin can whirled on the end of a string moves in a circle because a. the can continually pulls on the string. b. once the can starts moving, that is its natural tendency. c. there is a force on the can pulling it outward. d. there is an inward force acting on the can. e. all of the above

D

The circular orbit of a satellite orbiting Earth is characterized by a constant _____. a. speed b. radius c. magnitude of acceleration d. all of the above e. none of the above

D

The gravitational force between two massive spheres a. is always an attraction. b. depends on how massive they are. c. depends inversely on the square of the distances between them. d. all of the above

D

Where does a satellite in a circular orbit have the greatest kinetic energy? a. At the point farthest from the planet b. Exactly at the point halfway to the planet c. At the point closest to the planet d. Anywhere—its kinetic energy is constant e. More information is needed

D

A 1000-kg car is moving at 30 m/s around a horizontal unbanked curve whose radius is 0.10 km. What is the magnitude of the friction force required to keep the car from sliding? a. 900 N b. 300 N c. 9800 N d. 3000 N e. 9000 N

E

A 2.0-kg ball is moving with a constant speed of 5.0 m/s in a horizontal circle whose radius is 0.5 m. What is the magnitude of the net force on the ball? a. 20 N b. 50 N c. 40 N d. 0 N e. 100 N

E

Consider the gravitational force between Earth and a meteor in outer space. If the meteor moves so its distance from the Earth's center doubles, the gravitational force on the meteor will be _____. a. quadruple b. double c. eight times greater d. half e. one quarter

E

What remains constant for a satellite in an elliptical orbit? a. Its speed b. Its potential energy c. Its distance from the planet d. Its kinetic energy e. Its total energy

E

Because Earth and moon are gravitationally attracted toward each other, they will soon collide. True False

False

Because Earth is "falling" around the sun, it will eventually crash into it. True False

False

Because a satellite is always changing direction, it loses energy as it orbits Earth. True False

False

If Earth were its present size but twice as massive, we would weigh less. True False

False

If Earth were to disappear, the moon would still orbit the place where Earth was. True False

False

The gravitational force of Earth on an object does not depend upon the object's mass. True False

False

The only reason riders on a rotating platform in a carnival ride don't fall out is because they are strapped in. True False

False

The speed of a satellite in a circular orbit around Earth changes as it circles Earth. True False

False

The sum of a satellite's kinetic energy and potential energy varies as the satellite orbits a planet. True False

False

A straight line about which rotation takes place is called an axis. True False

True

An Earth satellite is a projectile that falls around Earth instead of falling into it. True False

True

For some massive stars, gravitational collapse doesn't stop until the density of the star becomes so enormous that even light cannot escape. Such a star becomes a black hole. True False

True

The component of an orbiting satellite's velocity that is parallel to Earth's surface is its tangential velocity. True False

True

The force on a ball decreases as the ball moves farther from Earth. True False

True

There is a force on Earth that is directed toward the sun. True False

True

When you whirl a can on the end of a string, the centripetal force on the can is actually the pull of the string on the can. True False

True