Deck 9: Gravity

Question 1

An object is placed exactly halfway between the Earth and moon.The object will fall toward the

A)Earth.
B)moon.
C)neither of these

Answer 1

Earth.

Question 2

A black hole is

A)an empty region of space with a huge gravitational field.
B)a small region that contains the mass of many galaxies.
C)simply the remains of a giant star that has undergone gravitational collapse.

Answer 2

simply the remains of a giant star that has undergone gravitational collapse.

Question 3

The Earth's gravitational field extends

A)only above and beyond the Earth's surface and cancels inside the Earth.
B)both inside and outside the Earth and throughout the entire universe.
C)neither of these

Answer 3

both inside and outside the Earth and throughout the entire universe.

Question 4

If your mass,the mass of the Earth,and the mass of everything in the solar system were twice as much as it is now,yet everything stayed the same size,your weight on Earth would

A)be the same.
B)double.
C)quadruple.
D)be eight times as much as now.
E)none of these

Question 5

Inside a freely falling elevator,there would be no

A)gravitational force on you.
B)apparent weight for you.
C)both of these
D)none of these

Question 6

The amount of gravitational force that acts on the space shuttle while in orbit is

A)nearly zero.
B)almost as much as the shuttle's weight on the Earth's surface.
C)the same as the shuttle's weight on the Earth's surface.

Question 7

If the Earth's mass decreased to one-half its original mass with no change in radius,then your weight would

A)decrease to one quarter your original weight.
B)decrease to one half your original weight.
C)stay the same.
D)none of these

Question 8

What is the force of gravity on a 500-newton woman standing on the Earth's surface?

A)50 N
B)250 N
C)500 N
D)5000 N
E)none of these

Question 9

According to Newton,doubling the distance between two interacting objects

A)divides by 2 the gravitational force between them.
B)multiplies by 2 the gravitational force between them.
C)divides by 4 the gravitational force between them.
D)multiplies by 4 the gravitational force between them.

Question 10

If the mass of the Earth somehow increased with no change in radius,your weight would

A)increase also.
B)decrease.
C)stay the same.

Question 11

An asteroid exerts a 360-N gravitational force on a nearby spacecraft.This force is directed

A)toward the asteroid.
B)away from the asteroid.
C)toward the sun.

Question 12

An asteroid exerts a 360-N gravitational force on a nearby spacecraft.If the spacecraft moves to a position three times as far from the center of the asteroid,the force will be

A)zero.
B)40 N.
C)120 N.
D)360 N.
E)1080 N.

Question 13

The concept of force is not fundamental to

A)Newton's theory of gravitation.
B)Einstein's theory of gravitation.
C)both of these
D)neither of these

Question 14

Consider two planets in space that gravitationally attract each other.If the masses of both planets are doubled,and the distance between them is also doubled,then the force between them is

A)one quarter.
B)half as much.
C)twice as much.
D)four times as much.
E)none of these

Question 15

The direction of a gravitational field is

A)in the same direction as the gravitational attraction.
B)away from the center of gravity of an object.
C)opposite to the direction of gravitational attraction.

Question 16

If the sun were twice as massive

A)its pull on the Earth would double.
B)the pull of the Earth on the sun would double.
C)both of these
D)neither of these

Question 17

If the radius of the Earth somehow decreased with no change in mass,your weight would

A)increase.
B)not change.
C)decrease.

Question 18

Newton discovered

A)gravity.
B)that gravity is universal.
C)neither

Question 19

According to Newton,the greater the masses of interacting objects,the

A)less the gravitational force between them.
B)greater the gravitational force between them.
C)greater the force between them by the square of the masses.

Question 20

A weight watcher who normally weighs 400 N stands on top of a very tall ladder so she is one Earth radius above the Earth's surface.How much would she weigh there?

A)0
B)100 N
C)200 N
D)400 N
E)none of these

Question 21

The reason the moon does not crash into the Earth is that the

A)Earth's gravitational field is weak at the moon.
B)gravitational pull of other planets keeps the moon up.
C)moon has a sufficient tangential speed.
D)moon has less mass than the Earth.
E)none of these

Question 22

No force due to Earth's gravity is acting on the astronauts inside the orbiting space shuttle.This statement is

A)always true while in orbit.
B)sometimes true while in orbit.
C)always false.

Question 23

The factor most directly responsible for making a black hole invisible is its

A)size.
B)mass.
C)color.
D)surface escape velocity.
E)none of these

Question 24

Half way to the center of a completely hollow planet with a thin uniform shell,your weight would be

A)one-quarter of your weight on the surface.
B)one-half of your weight on the surface.
C)three-quarters of your weight on the surface.
D)the same as at the surface.
E)zero.

Question 25

Passengers in a high-flying jumbo jet feel their normal weight in flight,while passengers in the orbiting space shuttle do not.This is because passengers in the space shuttle are

A)beyond the main pull of Earth's gravity.
B)above the Earth's atmosphere.
C)without support forces.
D)all of these
E)none of these

Question 26

Two objects move toward each other because of gravity.As the objects get closer and closer,the force between them

A)increases.
B)decreases.
C)increases,then decreases.
D)decreases,then increases.
E)remains constant.

Question 27

If a block is set sliding on a huge frictionless plane in contact with the Earth,it will NOT continue to move at constant speed because

A)of its inertia.
B)gravity will pull in a non-perpendicular direction as the block gets farther out on the plane.
C)gravity gets weaker as distance increases.
D)it is not free from the shackles of Earth's gravity.

Question 28

When a star collapses to form a black hole,its mass

A)increases.
B)decreases.
C)remains the same.

Question 29

The force of gravity acts on all apples on an apple tree.Some apples are twice as far from the ground as others.These twice-as-high apples,for the same mass,have

A)1/4 the weight.
B)1/2 the weight.
C)practically the same weight.

Question 30

If the sun collapsed to a black hole,the Earth's gravitational attraction to it would be

A)more.
B)less.
C)the same.

Question 31

Inside a freely falling runaway elevator,your

A)acceleration is zero.
B)apparent weight is zero.
C)gravitational interaction with the Earth is zero.
D)all of these
E)none of these

Question 32

The Earth is currently accelerating toward the sun (centripetal acceleration).If the sun collapsed into a black hole,this acceleration would

A)increase.
B)decrease.
C)stay the same.
D)cease to exist.

Question 33

Half way to the center of a planet of uniform density,your weight compared to that at the surface would be

A)one-quarter.
B)one-half.
C)three-quarters.
D)the same as at the surface.
E)zero.

Question 34

If you drop a stone into a hole drilled all the way to the other side of the Earth (neglect the molten core),the stone will

A)come to an abrupt stop at the center of the Earth.
B)speed up until it gets to the center of the Earth.
C)speed up until it reaches the other side of the Earth.
D)slow down until it reaches the center.

Question 35

The force of gravity acting on you will increase if you

A)burrow deep inside the planet.
B)stand on a planet with a radius that is shrinking.
C)both of these
D)none of these

Question 36

A very massive object A and a less massive object B move toward each other under the influence of gravitation.Which force,if either,is greater?

A)the force on A
B)the force on B
C)Both forces are the same.

Question 37

Two objects move toward each other because of gravity.As the objects get closer and closer,the acceleration of each

A)increases.
B)decreases.
C)remains constant.

Question 38

A long,perfectly level,frictionless bowling alley,over 2000 meters long,is built by a group of students as a class project.The center of the alley just touches the Earth near their school and the ends of the alley extend tangentially into outer space.A bowling ball released at either end starts rolling towards the center of the alley and will continue moving

A)indefinitely.
B)until it strikes the pins at the far end and stops.
C)for a while but slows to a stop before reaching the pins.

Question 39

The planet Jupiter is about 300 times as massive as Earth,yet on its surface you would weigh only about 3 times as much.This is because

A)your mass is 100 times less on Jupiter.
B)Jupiter is significantly farther from the sun.
C)Jupiter's radius is 10 times the Earth's radius.
D)you are 100 times more weightless there.
E)none of these

Question 40

When the distance between two stars decreases by half,the force between them

A)decreases by one-quarter.
B)decreases by one-half.
C)increases to twice as much.
D)increases to four times as much.
E)stays the same.

Question 41

If the sun somehow became twice as massive,your weight as normally measured here on Earth would

A)double.
B)quadruple.
C)not change.

Question 42

Suppose the moon had twice as much mass as it now does and still orbited the Earth at the same distance.In that case,the ocean bulges on Earth would be

A)larger.
B)smaller.
C)unequal in size.
D)not significantly different.
E)none of these

Question 43

On a given day,tides rise and fall at

A)the same time everywhere.
B)the same distance everywhere.
C)different times and different distances almost everywhere.
D)the same time and the same distance everywhere.

Question 44

Which is most responsible for the ocean tides?

A)the moon
B)the sun
C)Both contribute equally.

Question 45

The Earth is closer to the sun in January than in July,which accounts for the fact that the highest high tides in the northern hemisphere occur in

A)winter.
B)spring.
C)summer.
D)no particular time because tides do not depend on seasons.

Question 46

The best time for digging clams (when the low tide is extra low)is during the time of the

A)new or full moon.
B)half moon.
C)quarter moon.
D)none of these times in particular

Question 47

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)buy at a high altitude and sell at a low altitude.
B)buy at a low altitude and sell at a high altitude.
C)disregard altitude because it makes no difference.

Question 48

How far must one travel to get away from the Earth's gravitational field?

A)to a region above the Earth's atmosphere
B)to a region well beyond the moon
C)to a region beyond the solar system
D)Forget it;you can't travel far enough.

Question 49

Which pulls on the oceans of the Earth with the greater force?

A)the moon
B)the sun
C)Both pull the same.

Question 50

The origin of any micro tides in the human body is most likely the

A)sun.
B)moon.
C)Earth.

Question 51

A hollow spherical planet is inhabited by people who live inside it,where the gravitational field is zero.When a very massive space ship lands on the planet's surface,inhabitants find that the gravitational field inside the planet is

A)still zero.
B)non-zero,directed toward the spaceship.
C)non-zero,directed away from the spaceship.

Question 52

Tidal forces in general are the result of

A)two or more sources of gravitation.
B)a combination of any kind of forces acting on a body.
C)unequal forces acting on different parts of a body.
D)the inverse-square law.
E)unequal fluid flow.

Question 53

Which of these three produces the greatest tidal effect on you right now?

A)the moon
B)the sun
C)the Earth

Question 54

For lunar tides to occur in the human body

A)most of the body would have to be in the liquid state.
B)the Earth's gravitation would have to be incredibly small.
C)parts of the body would have to be appreciably closer to the moon than other parts.
D)But there are lunar tides in the body,as evidenced by women's monthly menstrual cycles.
E)none of these

Question 55

The main reason ocean tides exist is that the pull of the moon

A)and sun are in conjunction at high tides and in opposition at low tides.
B)is greater on oceans closer to the moon and less on oceans farther from the moon.
C)is greater on the Earth because the moon is closer to Earth.
D)and the sun on the oceans are in opposite directions.
E)none of these

Question 56

Each of us weighs a tiny bit less inside the ground floor of a skyscraper than we do on the ground away from the skyscraper.The reason for this is the

A)gravitational field is shielded inside the building.
B)mass of the building attracts us upward slightly.
C)both of these
D)none of these

Question 57

Which produces a greater tidal effect in your body,the moon or a 1-kg melon held above your head?

A)the moon
B)the melon
C)Not enough information is given to make a reasonable estimate.

Question 58

When you step on a weighing scale at noon,the Earth pulls you down and the overhead sun pulls you upward.The reason the sun's pull doesn't decrease your weight at noon is because

A)the sun's pull on you is negligibly small.
B)the weighing scale is calibrated only in Earth weight.
C)you,the scale,and the Earth are in free fall (in orbit)around the sun.
D)the sun's pull is cancelled by the gravitation of other celestial bodies.
E)of tidal effects in the "solid" Earth.

Question 59

We do not observe tides in a community swimming pool because

A)gravitation on the small mass of water is negligibly small.
B)it is shallow compared to the ocean.
C)all parts of it are practically the same distance from the moon.
D)they are masked by the much stronger pull of Earth gravity.
E)the tides are only observed at night.

Question 60

During an eclipse of the sun the high ocean tides on Earth are

A)extra high.
B)extra low.
C)not particularly different.

Question 61

If the moon were four times as massive but twice as far from Earth,high tides on Earth would be

A)higher.
B)lower.
C)no different.

Question 62

All places on the Earth would have high tides at the same instant if the

A)moon did not revolve.
B)moon did not rotate.
C)sun did not revolve.
D)sun did not rotate.
E)None of the above choices are correct.

Question 63

Suppose the moon had twice the diameter but the same mass and same orbital distance from Earth.In that case,the high tides on Earth would be

A)higher.
B)lower.
C)unequal in size.
D)practically the same.
E)none of these

Question 64

If the moon were covered with water,tidal effects caused by the Earth would find the moon with

A)1 tidal bulge.
B)2 tidal bulges.
C)3 tidal bulges.
D)4 tidal bulges.
E)no tidal bulges.

Question 65

There would be only one ocean tide per 24-hour day if the

A)Earth and moon were equally massive.
B)moon were more massive than the Earth.
C)sun's influence on the tides were negligible.
D)moon's mass were small - only a few kilograms.
E)none of these