Deck 9: Gravity

Question 1

If Earth's radius somehow increased with no change in mass, your weight would

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

Answer 1

decrease.

Question 2

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

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

Answer 2

increases.

Question 3

According to Newton, when the distance between two interacting objects doubles, the gravitational force is

A)half.
B)one-quarter.
C)the same.
D)twice as much.
E)four times as much.

Answer 3

one-quarter.

Question 4

The force of Earth's gravity on a capsule in space increases as it comes closer. When the capsule moves to half its distance, the force toward Earth is then

A)twice.
B)three times greater.
C)four times greater.
D)none of the above

Question 5

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

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

Question 6

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

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

Question 7

As two objects moving toward each other due to gravity get closer, the acceleration of each

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

Question 8

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

A)decrease to one-quarter.
B)decrease to half.
C)stay the same.
D)none of the above

Question 9

Newton discovered

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

Question 10

Two planets in space gravitationally attract each other. If both the masses and distances are doubled, the force between them is

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

Question 11

If the Sun were twice as massive

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

Question 12

If a block is set sliding on a huge imaginary frictionless plane in contact with Earth's surface, it will NOT sustain a constant speed because

A)a component of gravitational force parallel to the plane soon acts on it.
B)gravity gets weaker as distance increases.
C)it is not free from the shackles of Earth's gravity.
D)of its inertia.

Question 13

In comparison with other fundamental forces, the universal gravitational constant G indicates that gravity is

A)very weak.
B)strong.
C)very strong.

Question 14

The universal gravitational constant G was first measured

A)before Newton's time.
B)by Newton himself.
C)after Newton's time.

Question 15

To make a profit a buyer purchases metal by weight at one altitude and sells 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)it makes no difference.

Question 16

When the distance between two stars decreases by one-third, the force between them

A)decreases by one-third.
B)decreases by one-half.
C)increases to twice as much.
D)increases to nine times as much.
E)none of the above

Question 17

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

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

Question 18

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 19

The force of Earth's gravity on a capsule in space will lessen as it moves farther away. If the capsule moves to twice its distance, the force toward Earth becomes

A)half.
B)three-quarters.
C)one-fourth.
D)none of the above

Question 20

The difference between Newton's law as a proportion and an equation involves

A)the constant G.
B)the equal sign.
C)one being a vector and the other not.
D)magnitude and direction.

Question 21

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

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

Question 22

The main reason ocean tides exist is that Moon's pull is stronger

A)than the pull of the Sun.
B)on water closer to it than on water farther away.
C)on Earth's oceans than on Earth itself.
D)all of the above

Question 23

Inside a freely-falling elevator, you would have no

A)gravitational force on you.
B)weight.
C)both of these
D)neither of these

Question 24

When you weigh yourself on a bathroom scale on a slight incline instead of a level surface, your weight reading on the scale will be

A)less.
B)no different.
C)more.

Question 25

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

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

Question 26

Inside a freely-falling runaway elevator, your

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

Question 27

Tidal bulges on the Moon involve the concept of

A)torques.
B)elasticity.
C)slight water on the Moon.
D)magnetism.

Question 28

Your weight is the force

A)due to gravity only.
B)you exert against a supporting surface.
C)equal to your normal force on any surface.

Question 29

Tides caused mainly by the Moon occur in Earth's

A)oceans.
B)atmosphere.
C)interior.
D)all of the above

Question 30

You can experience weight

A)standing on Earth's surface.
B)in an accelerating elevator away from Earth.
C)in a rotating habitat in space.
D)all of the above

Question 31

Which is most responsible for Earth's ocean tides?

A)Moon
B)Sun
C)both contribute equally.

Question 32

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 33

Passengers in a high-flying jumbo jet feel their normal weight in flight, while passengers in an orbiting space vehicle do not, because passengers in the space vehicle are

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

Question 34

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

A)Moon
B)Sun
C)both pull the same.

Question 35

One side of the Moon continually facing Earth is

A)a passing phenomenon.
B)a cosmic coincidence.
C)tidal lock.

Question 36

If you jounce up and down on a bathroom scale, what varies on the scale reading is

A)mg.
B)the normal force.
C)both of these
D)neither of these

Question 37

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

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

Question 38

If the Sun became twice as massive, your attraction to the Sun would double and your weight as measured on Earth would

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

Question 39

You experience weightlessness

A)in the absence of a supporting surface.
B)momentarily when you step off a chair.
C)in a freely falling elevator.
D)all of the above

Question 40

When you step on a weighing scale at noon, Earth pulls you downward 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 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 41

The concept of force is fundamental to

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

Question 42

Which produces a greater tidal effect in your body, the Moon or a 1-kg melon held at arm's length above your head?

A)the Moon
B)the melon
C)both about equally

Question 43

If the Moon had twice as much mass and still orbits Earth at the same distance, ocean bulges on Earth would be

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

Question 44

For lunar tides to occur in the human body

A)most of the body would have to be in the liquid state.
B)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)none of the above

Question 45

If the Moon were covered with water, tidal effects caused by 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 46

Earth's gravitational field extends

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

Question 47

All places on 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

Question 48

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

A)the Moon
B)the Sun
C)the Earth

Question 49

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 Earth.
C)Sun's influence on the tides were negligible.
D)Moon's mass were small - only a few kilograms.
E)none of the above

Question 50

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 the above

Question 51

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

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

Question 52

Surrounding a magnet is a magnetic field. Surrounding an electron is an electric field. Surrounding Earth is

A)an alteration in space in which mass experiences a force.
B)a gravitational field.
C)both of these
D)neither of these

Question 53

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)none of the above

Question 54

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

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

Question 55

The direction of a gravitational field is

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

Question 56

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 the above

Question 57

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 58

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 59

On each given day and location, tides rise and fall at

A)about the same time.
B)exactly the same time.
C)different times.
D)ever increasing rates daily.

Question 60

The origin of any microtides in the human body is most likely the

A)Sun.
B)Moon.
C)Earth.

Question 61

How far must one travel to escape Earth's gravitational field?

A)to a region above 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 62

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

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

Question 63

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 64

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 65

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 because the

A)gravitational field is shielded inside the building.
B)mass of the building above slightly attracts us upward.
C)both of these
D)neither of these

Question 66

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

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

Question 67

A black hole is

A)an empty region of space with a huge gravitational field.
B)at the center if all stars.
C)the remains of a giant star that has undergone gravitational collapse.

Question 68

Planets wobble in their orbits due to

A)the gravitational attraction to other planets.
B)uncertainties in the inverse-square law.
C)elliptical-orbit quirks.
D)all of the above
E)none of the above

Question 69

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 the above

Question 70

A hollow spherical planet is inhabited by people who live inside it, where the gravitational field is zero. When a very massive spaceship 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 71

Earth is presently accelerating toward the Sun (centripetal acceleration). If the Sun collapsed into a black hole, this acceleration would

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

Question 72

If your mass, the mass of 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 the above

Question 73

The amount of gravitational force that acts on a space vehicle while in Earth orbit is

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

Question 74

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 75

The force of gravity acting on you will increase if you

A)burrow deep inside Earth.
B)stand on a planet with a shrinking radius.
C)both of these
D)neither of these

Question 76

Rate this statement: No force due to Earth's gravity acts on astronauts inside the orbiting space station.

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

Question 77

If an object is placed exactly halfway between Earth and the Moon, it would fall toward the

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

Question 78

An outcome of universal gravitation is that

A)planets aren't cubes with sharp corners.
B)its discovery prompted other laws of nature.
C)prediction and discovery of planets.
D)all of the above

Question 79

Which rocket would require more fuel?

A)one going from the Moon to Earth.
B)one going from Earth to the Moon.
C)both the same.

Question 80

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

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