Chapter 9 Practice Problems

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

500 N

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

Less

Which is most responsible for Earth's ocean tides?

Moon

Wobbles in the path of Uranus led to the discovery of

Neptune

The concept of force is fundamental to

Newton's theory of gravitation.

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

None of the following: Moon did not revolve, Moon did not rotate, Sun did not revolve, Sun did not rotate.

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

None of the following: one-quarter, half as much, twice as much, four times as much.

One side of the Moon continually facing Earth is

Tidal lock

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

Very weak

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 component of gravitational force parallel to the plane soon acts on it.

The universal gravitational constant G was first measured

after Newton's time

We do not observe tides in a community swimming pool because

all parts of it are practically the same distance from the Moon.

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

always false

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

an alteration in space in which mass experiences a force, and a gravitational field.

Earth's gravitational field extends

both inside and outside Earth and throughout the entire universe.

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

buy at a high altitude and sell at a low altitude

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

forget it; you can't travel far enough.

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

four times greater

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

greater the gravitational force between them

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

lower

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

mass of the building above slightly attracts us upward.

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

nearly as much as the vehicle's weight on Earth's surface.

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

new or full moon

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

not change

Tides caused mainly by the Moon occur in Earth's

oceans, interior and atmosphere

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

on water closer to it than on water farther away.

Which rocket would require more fuel?

one going from Earth to the Moon.

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

one-fourth

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

one-half

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

one-quarter

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

practically the same

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

remains the same

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

speed up until it gets to Earth's center.

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

surface escape velocity.

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

the constant G

Planets wobble in their orbits due to

the gravitational attraction to other planets.

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

the melon

A black hole is

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

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

the same

Tidal bulges on the Moon involve the concept of

torques

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

toward the asteroid

Tidal forces in general are the result of

unequal forces acting on different parts of a body

Inside a freely-falling elevator, you would have no

weight

Inside a freely-falling runaway elevator, your

weight is zero.

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

without support forces

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

you, the scale, and Earth are in free fall (in orbit) around the Sun

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

zero

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

extra high

Pluto is classified by as a

Dwarf planet

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

Earth

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

Sun

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

The normal force

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

decrease

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

decrease to half

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

different times

You can experience weight

in a rotating habitat in space, standing on Earth's surface, and in an accelerating elevator away from earth

The direction of a gravitational field is

in the same direction as gravitational attraction.

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

increase also

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

increases

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

increases

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

increases to nine times as much

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

larger

You experience weightlessness

- in the absence of a supporting surface. - in a freely falling elevator. - momentarily when you step off a chair.

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?

100 N

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

2 tidal bulges.

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

40 N

An outcome of universal gravitation is that

All of the following: planets aren't cubes with sharp corners, its discovery prompted other laws of nature, prediction and discovery of planets.

Your weight is the force

B) you exert against a supporting surface

If the Sun were twice as massive

Both of these: its pull on Earth would double, the pull of Earth on the Sun would double.

The identities of dark energy and dark matter are

Both of theses: unknown at this time, subjects of intense astronomical interest.

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

C

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

Earth

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

None of the following: Earth and Moon were equally massive, Moon were more massive than Earth, Sun's influence on the tides were negligible, Moon's mass were small — only a few kilograms.

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?

both forces are the same

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

non-zero, directed toward the spaceship

For lunar tides to occur in the human body

parts of the body would have to be appreciably closer to the Moon than other parts.

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

practically the same weight

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

quadruple.

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

remain the same

The force of gravity acting on you will increase if you

stand on a planet with a shrinking radius.

Newton discovered

that gravity is universal

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

the Earth

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

winter