Question 1

The escape velocity on the Moon is less than that on Earth.

Accepted Answer

A) True 
 B)False  True

Question 2

An astronaut orbiting the Earth in a circular orbit at a constant speed does not feel the force of gravity because his or her acceleration is zero.

Accepted Answer

A) True 
 B)False  False

Question 3

The distance between Earth and the Moon is increasing because of:

Accepted Answer

A)  the expansion of the Universe 
B)  the expansion of the Solar System 
C)  tidal forces from the Moon 
D)  tidal forces from the Moon and Sun 
E)  dark energy 
A)  the expansion of the Universe 
B)  the expansion of the Solar System 
C)  tidal forces from the Moon 
D)  tidal forces from the Moon and Sun 
E)  dark energy C

Question 4

Show that the gravitational pull on Earth from the Sun is about 200 times the gravitational pull on Earth from the Moon. For reference, Moon's mass is 7.3 * 10 22 kg, the Sun's mass is 2 * 1030 kg, the Earth-Moon distance is 3.8 * 105 km, and the Earth-Sun distance is 1.5 * 108 km.

Accepted Answer

F_grav =GM₁M_2<

Question 5

What is the velocity one would need to give a satellite in order for it to escape from the Solar System (meaning escape the Sun's gravity) if it was launched from the Earth at a distance of 1 AU from the Sun? Give your answer in units of m/s.

Accepted Answer

The escape velocity from the S

Question 6

If an object is moving in a circular orbit at a constant speed, which of the following is FALSE?

Accepted Answer

A)  Its acceleration is not zero. 
B)  Its acceleration is zero. 
C)  Its velocity is not zero. 
D)  There is an unbalanced force acting on it. 
E)  All the above statements are true. 
A)  Its acceleration is not zero. 
B)  Its acceleration is zero. 
C)  Its velocity is not zero. 
D)  There is an unbalanced force acting on it. 
E)  All the above statements are true.

Question 7

Figure 1
-According to Figure 1, a high tide at a given location will occur ____ time(s) a day.

Accepted Answer

A)  one 
B)  three 
C)  two 
D)  four 
E)  eight 
A)  one 
B)  three 
C)  two 
D)  four 
E)  eight

Question 8

If you discovered a planet orbiting another star, and the planet had an orbital period of 2 years and a semimajor axis of 1 AU, what would be the mass of its parent star? You can assume the planet's mass is much less than the star's mass.

Accepted Answer

A)  0.25 M $\odot$ 
B)  0.5 M $\odot$ 
C)  1.0 M $\odot$ 
D)  1.25 M $\odot$ 
E)  2.0 M $\odot$ 
A)  0.25 M $\odot$ 
B)  0.5 M $\odot$ 
C)  1.0 M $\odot$ 
D)  1.25 M $\odot$ 
E)  2.0 M $\odot$

Question 9

Consider the Figure below that illustrates the tidal bulge on the Earth's oceans due to the Moon and Sun from an observer looking down on the North Pole of the Earth. At what phase of the Moon will the lowest tides of the year occur? Explain the rationale for your answer either in words or with a sketch.

Accepted Answer

The lowest tides of the year are called

Question 10

Two rocks (call them S and T) are released at the same time from the same height and start from rest. Rock S has 20 times the mass of rock T. Which rock will fall faster if the only forces involved are each rock's mutual gravitational attraction with Earth?

Accepted Answer

A)  Rock S 
B)  Rock T 
C)  Both rocks will fall at the same rate. 
D)  not enough information is available to answer 
A)  Rock S 
B)  Rock T 
C)  Both rocks will fall at the same rate. 
D)  not enough information is available to answer

Question 11

Is there a difference in your weight between when you are on top of a mountain at 1,000 meters above sea level compared to when you are sitting in a classroom at 10 meters above sea level?

Accepted Answer

Yes, you weigh less on the mountaintop b

Question 12

Figure 2
-According to Figure 2, spring tides occur when the lunar and solar tides _________ resulting in _________ tides.

Accepted Answer

A)  add; above average 
B)  partially cancel out; above average 
C)  add; below average 
D)  partially cancel out; below average 
E)  completely cancel out; no 
A)  add; above average 
B)  partially cancel out; above average 
C)  add; below average 
D)  partially cancel out; below average 
E)  completely cancel out; no

Question 13

Tidal forces are caused by:

Accepted Answer

A)  the weight of the water in the oceans on the ocean floor 
B)  the strength of the gravitation pull of the Moon on Earth 
C)  the difference between the weight of the water on the ocean floor at high and low tide 
D)  the difference between the strength of the gravitiational pull of the Moon and Sun on either side of Earth 
E)  the strength of the gravitation pull of the Moon and the Sun on Earth 
A)  the weight of the water in the oceans on the ocean floor 
B)  the strength of the gravitation pull of the Moon on Earth 
C)  the difference between the weight of the water on the ocean floor at high and low tide 
D)  the difference between the strength of the gravitiational pull of the Moon and Sun on either side of Earth 
E)  the strength of the gravitation pull of the Moon and the Sun on Earth

Question 14

Figure 2
-According to Figure 2, neap tides occur at which phases of the Moon?

Accepted Answer

A)  new and full 
B)  third quarter 
C)  first quarter and third quarter 
D)  full 
E)  new 
A)  new and full 
B)  third quarter 
C)  first quarter and third quarter 
D)  full 
E)  new

Question 15

The force of gravity between Saturn and the Sun is _________ the force of gravity between the Earth and the Sun. For reference, Saturn is approximately 100 times more massive than Earth, and the semimajor axis of Saturn's orbit is 10 AU.

Accepted Answer

A)  10 times smaller than 
B)  1,000 times larger than 
C)  1,000 times smaller than 
D)  100 times larger than 
E)  approximately equal to 
A)  10 times smaller than 
B)  1,000 times larger than 
C)  1,000 times smaller than 
D)  100 times larger than 
E)  approximately equal to

Question 16

Because of the Moon's tidal effect on the oceans, the Moon's orbital distance is shrinking and eventually the Moon will collide with the Earth.

Accepted Answer

A) True 
 B)False

Question 17

If you have two moons that have the same radius, but Moon A is denser and has 2 times the mass of Moon B, how do their escape velocities compare?

Accepted Answer

A)  Moon A has an escape velocity that is 1.4 times larger than Moon B. 
B)  Moon A has an escape velocity that is 1.4 times smaller than Moon B. 
C)  Moon A has an escape velocity that is 2 times smaller than Moon B. 
D)  Moon A has an escape velocity that is 2 times larger than Moon B. 
E)  Because gravity affects all masses the same, the escape velocities are the same. 
A)  Moon A has an escape velocity that is 1.4 times larger than Moon B. 
B)  Moon A has an escape velocity that is 1.4 times smaller than Moon B. 
C)  Moon A has an escape velocity that is 2 times smaller than Moon B. 
D)  Moon A has an escape velocity that is 2 times larger than Moon B. 
E)  Because gravity affects all masses the same, the escape velocities are the same.

Question 18

Mars has about one tenth the mass of Earth and half the Earth's radius. How does the acceleration of gravity on Mars compare to that on Earth?

Accepted Answer

g = GM/R²; thus g_M

Question 19

If we wanted to increase the Hubble Space Telescope's altitude above the Earth and keep it in a stable orbit, we also would need to:

Accepted Answer

A)  increase its orbital speed 
B)  increase its weight 
C)  decrease its weight 
D)  decrease its orbital speed 
E)  increase its mass 
A)  increase its orbital speed 
B)  increase its weight 
C)  decrease its weight 
D)  decrease its orbital speed 
E)  increase its mass

Question 20

The force of gravity between the Earth and the Sun is _________ the force of gravity between the Earth and the Moon. For reference, the average distance between the Earth and the Moon is 0.003 AU, the mass of the Moon is 7 * 1022 kg, and the mass of the Sun is 2 *1030 kg.

Accepted Answer

A)  86,000 times larger than 
B)  260 times larger than 
C)  140 times smaller than 
D)  6,400 times smaller than 
E)  the same as 
A)  86,000 times larger than 
B)  260 times larger than 
C)  140 times smaller than 
D)  6,400 times smaller than 
E)  the same as

Exam 4: Gravity and Orbits

The escape velocity on the Moon is less than that on Earth.

An astronaut orbiting the Earth in a circular orbit at a constant speed does not feel the force of gravity because his or her acceleration is zero.

The distance between Earth and the Moon is increasing because of:

Show that the gravitational pull on Earth from the Sun is about 200 times the gravitational pull on Earth from the Moon. For reference, Moon's mass is 7.3 * 10 22 kg, the Sun's mass is 2 * 1030 kg, the Earth-Moon distance is 3.8 * 105 km, and the Earth-Sun distance is 1.5 * 108 km.

What is the velocity one would need to give a satellite in order for it to escape from the Solar System (meaning escape the Sun's gravity) if it was launched from the Earth at a distance of 1 AU from the Sun? Give your answer in units of m/s.

If an object is moving in a circular orbit at a constant speed, which of the following is FALSE?

Figure 1 -According to Figure 1, a high tide at a given location will occur ____ time(s) a day.

If you discovered a planet orbiting another star, and the planet had an orbital period of 2 years and a semimajor axis of 1 AU, what would be the mass of its parent star? You can assume the planet's mass is much less than the star's mass.

Two rocks (call them S and T) are released at the same time from the same height and start from rest. Rock S has 20 times the mass of rock T. Which rock will fall faster if the only forces involved are each rock's mutual gravitational attraction with Earth?

Is there a difference in your weight between when you are on top of a mountain at 1,000 meters above sea level compared to when you are sitting in a classroom at 10 meters above sea level?

Figure 2 -According to Figure 2, spring tides occur when the lunar and solar tides _________ resulting in _________ tides.

Tidal forces are caused by:

Figure 2 -According to Figure 2, neap tides occur at which phases of the Moon?

The force of gravity between Saturn and the Sun is _________ the force of gravity between the Earth and the Sun. For reference, Saturn is approximately 100 times more massive than Earth, and the semimajor axis of Saturn's orbit is 10 AU.

Because of the Moon's tidal effect on the oceans, the Moon's orbital distance is shrinking and eventually the Moon will collide with the Earth.

If you have two moons that have the same radius, but Moon A is denser and has 2 times the mass of Moon B, how do their escape velocities compare?

Mars has about one tenth the mass of Earth and half the Earth's radius. How does the acceleration of gravity on Mars compare to that on Earth?

If we wanted to increase the Hubble Space Telescope's altitude above the Earth and keep it in a stable orbit, we also would need to:

The force of gravity between the Earth and the Sun is _________ the force of gravity between the Earth and the Moon. For reference, the average distance between the Earth and the Moon is 0.003 AU, the mass of the Moon is 7 * 1022 kg, and the mass of the Sun is 2 *1030 kg.

Why Learn Astronomy

Patterns in the Skymotions of Earth

Motion of Astronomical Bodies

Light

The Tools of the Astronomer

The Birth and Evolution of Planetary Systems

The Terrestrial Planets and Earths Moon

Atmospheres of the Terrestrial Planets

Worlds of Gas and Liquid the Giant Planets

Planetary Adornmentsmoons and Rings

Dwarf Planets and Small Solar System Bodies

Taking the Measure of Stars

Our Starthe Sun

Star Formation and the Interstellar Medium

Evolution of Low-Mass Stars

Evolution of High-Mass Stars

Relativity and Black Holes

The Expanding Universe

Galaxies

The Milky Waya Normal Spiral Galaxy

Modern Cosmology

Large-Scale Structure in the Universe

Life

Filters

Show that the gravitational pull on Earth from the Sun is about 200 times the gravitational pull on Earth from the Moon. For reference, Moon's mass is 7.3 * 10 ²² kg, the Sun's mass is 2 * 10³⁰ kg, the Earth-Moon distance is 3.8 * 10⁵ km, and the Earth-Sun distance is 1.5 * 10⁸ km.

Figure 2 -According to Figure 2, spring tides occur when the lunar and solar tides _ resulting in _ tides.

The force of gravity between the Earth and the Sun is _________ the force of gravity between the Earth and the Moon. For reference, the average distance between the Earth and the Moon is 0.003 AU, the mass of the Moon is 7 * 10²² kg, and the mass of the Sun is 2 *10³⁰ kg.