Chapter 4 part 2

Which of the following represents a change from potential energy to kinetic energy?

A rock starting from rest on a high cliff, then moving faster and faster as it falls.

According to the law of universal gravitation, what would happen to Earth if the Sun were somehow replaced by a black hole of the same mass?

Earth's orbit would not change.

As you watch the video, notice that the size of the tidal bulges varies with the Moon's phase, which depends on its orbital position relative to the Sun. Which of the following statement(s) accurately describe(s) this variation?

Low tides are lowest at both full moon and new moon. High tides are highest at both full moon and new moon.

As shown in the video, Earth has two tidal bulges at all times. Approximately where are these bulges located?

One faces the Moon and one faces opposite the Moon.

Einstein's theory, like Newton's, predicts that, in the absence of air resistance, all objects should fall at the same rate regardless of their masses. Consider the following hypothetical experimental results. Which one would indicate a failure of Einstein's theory?

Scientists dropping balls on the Moon find that balls of different mass fall at slightly different rates.

One tidal bulge faces toward the Moon because that is where the gravitational attraction between Earth and the Moon is strongest. Which of the following best explains why there is also a second tidal bulge?

The second tidal bulge arises because gravity weakens with distance, essentially stretching Earth along the Earth-Moon line.

In considering the Earth-Moon system we find

There are tidal forces on the moon by the Earth There are tidal forces on the Earth caused by the Moon There are tidal forces on Earth and Moon caused by the Sun, but the Suns tidal influence is less than the Earths on the Moon or the Moon's on the Earth

If an astronaut goes on a space walk outside the Space Station, she will quickly float away from the station unless she has a tether holding her to the station. (t/f)

This statement is false. She and the Space Station share the same orbit and will stay together unless they are pushed apart.

Which of the following best describes the origin of ocean tides on Earth?

Tides are caused by the difference in the force of gravity exerted by the Moon across the sphere of the eart

the moon is constantly falling towards earth (t/f)

True

Most people are familiar with the rise and fall of ocean tides. Do tides also affect land?

Yes, though land rises and falls by a much smaller amount than the oceans.

According to what we now know from Newton's laws, which of the following best explains why Keplers second law is true?

a planets angular momentum must be conserved as it moves around its orbit

You have found that tides on Earth are determined primarily by the position of the Moon, with the Sun playing only a secondary role. Why does the Moon play a greater role in causing tides than the Sun?

because the gravitational attraction between Earth and the Moon varies more across Earth than does the gravitational attraction between Earth and the Sun

At which lunar phase(s) are tides least pronounced (e.g., the lowest high tides)?

both first and third quarters

At which lunar phase(s) are tides most pronounced (e.g., the highest high tides)?

both new and full Moons

According to the universal law of gravitation, if you triple the distance between tow objects then the gravitational force between them will

decrease by a factor of 9

Suppose two objects are attracting each other gravitationally. If you double the distance between them, the strength of their gravitational attraction __________.

decreases by a factor of 4

The allowed shapes for orbits under the force of gravity are

ellipses, parabolas, and hyperbolas.

Doubling the distance between two objects halves the gravitational force between them (t/f)

false

Process of science: gravity only affects very massive objects and we can therefore only test theories about it when looking at the orbits of plants (t/f)

false

there is no gravity in space (t/f)

false

which of the following are allowed orbital paths under gravity

hyperbolic, elliptical, parabolic

As a giant cloud of gas collapses due to gravity, you would expect its rate of rotation to

increase

According to the universal law of gravitation if you double the masses of both attracting objects, then the gravitational force between them will

increase by a factor of 4

according to the universal law of gravitation, the force due to gravity is

inversely proportional to the square of the distance between objects

Why is newtons version of Keplers third law so useful to astronomers?

it can be used to determine the masses of many distant objects

the mass of jupiter can be calculated by

measuring the orbital period and distance of one of jupiters moons

If Earth were twice as far from the Sun, the force of gravity attracting Earth to the Sun would be:

one-quarter as strong.

Consider Earth and the Moon. As you should now realize, the gravitational force that Earth exerts on the Moon is equal and opposite to that which the Moon exerts on Earth. Therefore, according to Newton's second law of motion ___

the Moon has a larger acceleration than Earth, because it has a smaller mass

we one see on face of the Moon from Earth because

the Moon is already tidally locked to the Earth

The center of mass of a binary star system is

the balance point system, around which the two objects would revolve

Tidal forces on Earth are causing

the earth to slow down its rotation rate

The Moon is slowly moving away from Earth. (t/f)

true

The center of mass for Earth orbiting the Sun lies inside the sun (t/f)

true

Any particular location on Earth experiences __________.

two high tides and two low tides each day