Chapter 4

Question 1

How would your weight change if Earth’s mass suddenly doubled, but its size
stayed the same?
A. Your weight would increase by a factor of 4.
B. Your weight would decrease by a factor of 4.
C. Your weight would increase by a factor of 2.
D. Your weight would decrease by a factor of 2.

Question 2

How would your weight change if Earth’s size suddenly doubled, but its mass
stayed the same?
A. Your weight would increase by a factor of 4.
B. Your weight would decrease by a factor of 4.
C. Your weight would increase by a factor of 2.
D. Your weight would decrease by a factor of 2.

Question 3

Astronauts experience weightlessness because
A. there is no gravity in space.
B. they are in microgravity.
C. they are freely falling around the Earth.
D. the Moon’s gravitational pull on them cancels out the Earth’s gravitational
pull.

Answer 3

C. they are freely falling around the Earth.

Question 4

Suppose you want to move a satellite farther away from the Earth, but you want
it to maintain a perfectly circular orbit. How should the satellite’s orbital speed
change?
A. It should decrease because the radius of the orbit is increasing.
B. It should increase because the radius of the orbit is increasing.
C. It will stay the same because orbital speed does not depend on distance.
D. This is impossible. It will enter into an elliptical orbit.

Question 5

Mars has two very small moons. Suppose Mars had an ocean. Would Mars have
tides similar in strength to Earth?
A. yes, due to the Sun
B. yes, due to the Sun and the two moons
C. No. The moons are too small, and Mars is too far away from the Sun for a
large effect.
D. No. The tides due to the two moons would cancel each other out.

Question 6

Why is there a high tide on the side of Earth farthest away from the Moon?
A. The Moon slingshots the water around Earth.
B. The Moon pulls Earth closer to it than it pulls the water on the far side.
C. The Moon pushes the water away on the far side .
D. There isn’t; the water is only high on the close side of Earth.

Answer 6

B. The Moon pulls Earth closer to it than it pulls the water on the far side.

Question 7

When Galaxy A is very close to Galaxy B, tidal tails are caused because
A. the gas on one side of the galaxies will be closer and feel stronger gravity
than on the far side of the galaxies.
B. the gas from Galaxy A and Galaxy B is magnetically attracted, causing it to
stretch together.
C. turbulence from the interaction is causing the gas to swirl out of the
galaxies.
D. the galaxies are moving very fast, leaving some gas behind.

Answer 7

A. the gas on one side of the galaxies will be closer and feel stronger gravity
than on the far side of the galaxies.

Question 8

Which tidal effect is the greatest?
A. Moon on Earth
B. Earth on Moon
C. Earth on Sun
D. Sun on Earth

Answer 8

A. Moon on Earth

Question 9

If an exoplanet is tidally locked to its star, that means
A. it is in a circular orbit.
B. it is orbiting very quickly.
C. only one side of the planet would ever get sunlight.
D. tidal locking doesn’t happen to planets.

Question 10

If the distance between Earth and the Sun were cut in half, the
gravitational force between them would:
A. decrease by a factor of 4
B. decrease by a factor of 2
C. increase by a factor of 2
D. increase by a factor of 4

Answer 10

D. increase by a factor of 4

Question 11

If Earth shrank to a smaller radius but kept the same mass, would the
gravitational force between Earth and the Moon:
A. decrease
B. increase
C. stay the same
Would everyone’s weight at the Earth’s Surface
A. increase
B. decrease
C. stay the same

Answer 11

C. stay the same, A. increase

Question 12

Rank the circular velocities of the following objects from smallest to
largest:
A. a 5-kg object orbiting Earth halfway to the Moon
B. a 10-kg object orbiting Earth just above Earth’s surface
C. a 15-kg object orbiting Earth at the same distance as the Moon

Answer 12

C. a 15-kg object orbiting Earth at the same distance as the Moon
A. a 5-kg object orbiting Earth halfway to the Moon
B. a 10-kg object orbiting Earth just above Earth’s surface

Question 13

Rank the following in order of weakest to strongest total tides:
A. new Moon in July
B. first quarter Moon in July
C. full Moon in January
D. third quarter Moon in January

Answer 13

D. third quarter Moon in January
B. first quarter Moon in July
A. new Moon in July
C. full Moon in January

Question 14

The Moon always keeps the same face toward Earth because of:
A. tidal locking
B. tidal forces from the Sun
C. tidal forces from Earth and the Sun

Answer 14

A. tidal locking

Question 15

What is tidal locking?