Question 1

The average distance between a planet and the Sun is given by the __________ of its elliptical orbit.

Accepted Answer

A)  radius 
B)  minor axis 
C)  eccentricity 
D)  semimajor axis 
A)  radius 
B)  minor axis 
C)  eccentricity 
D)  semimajor axis

Question 2

If a satellite sent to Mars is designed to return a rock sample to Earth,how fast must the satellite be launched from its surface in order to escape Mars's gravity? For reference,Mars has a mass of   and a radius of 2,400 km.

Accepted Answer

A)  100 m/s 
B)  6,000 m/s 
C)  20 m/s 
D)  You must know the mass of the satellite to determine the answer. 
A)  100 m/s 
B)  6,000 m/s 
C)  20 m/s 
D)  You must know the mass of the satellite to determine the answer.

Question 3

How much stronger is the gravitational force of the Sun on the Earth compared to the gravitational force of the Sun on Pluto? Note that Pluto's semimajor axis is 40 AU and its mass is 0.002 times the mass of the Earth.

Accepted Answer

The force of gravity between a

Question 4

If you found an exoplanet whose mass was the same as Jupiter's,but the planet orbited its star with a period of 2 years and a semimajor axis of 1 AU,what would be the mass of its star? For reference,Jupiter has a semimajor axis of 5.4 AU and an orbital period of 12 years.

Accepted Answer

A)    
B)    
C)    
D)    
A)    
B)    
C)    
D)

Question 5

An empirical science is one that is based on

Accepted Answer

A)  assumptions. 
B)  calculus. 
C)  computer models. 
D)  observed data. 
A)  assumptions. 
B)  calculus. 
C)  computer models. 
D)  observed data.

Question 6

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. 
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.

Question 7

The time it takes a planet to complete one full orbital revolution is commonly known as its

Accepted Answer

A)  period. 
B)  frequency. 
C)  orbital domain. 
D)  velocity. 
A)  period. 
B)  frequency. 
C)  orbital domain. 
D)  velocity.

Question 8

Kepler's third law can be expressed mathematically as

Accepted Answer

A)    . 
B)    . 
C)    . 
D)    . 
A)    . 
B)    . 
C)    . 
D)    .

Question 9

Even though they move at faster average speeds,the outer planets in the Solar System have longer periods than the inner planets because they are so far from the Sun that their orbits are enormous.

Accepted Answer

A) True 
 B)False

Question 10

When the geocentric model of the solar system did not match the observed positions of the planets,

Accepted Answer

A)  Tycho Brahe made measurements of higher accuracy and showed the geocentric model was correct. 
B)  Ptolemy added epicycles to the geocentric model to match the observed data. 
C)  Galileo argued that the Sun revolved around the Earth. 
D)  Kepler was inspired to create the theory of gravity. 
A)  Tycho Brahe made measurements of higher accuracy and showed the geocentric model was correct. 
B)  Ptolemy added epicycles to the geocentric model to match the observed data. 
C)  Galileo argued that the Sun revolved around the Earth. 
D)  Kepler was inspired to create the theory of gravity.

Question 11

In a period of three months,a planet travels 30,000 km with an average speed of 10.5 km/s.Some time later,the same planet travels 65,000 km in three months.How fast is the planet traveling at this later time? During which period is the planet closer to the Sun?

Accepted Answer

At the later time,because the planet is

Question 12

Astronauts feel "weightless" on the Moon.Using Newton's universal law of gravitation,explain why this statement is true or false and why astronauts experience this feeling.

Accepted Answer

Because the mass of the Moon is smaller

Question 13

Two rocks (call them S and T)are a distance of 50 km from one another.Rock S has 20 times the mass of rock T.Which rock will move faster if the only force involved is their mutual gravitational attraction?

Accepted Answer

A)  Rock S 
B)  Both rocks will move at the same speed. 
C)  Rock T 
D)  Not enough information is available to answer. 
A)  Rock S 
B)  Both rocks will move at the same speed. 
C)  Rock T 
D)  Not enough information is available to answer.

Question 14

If Jupiter has an orbital period of 12 years,what is its average distance from the Sun?

Accepted Answer

A)  2 AU 
B)  25 AU 
C)  10 AU 
D)  5 AU 
A)  2 AU 
B)  25 AU 
C)  10 AU 
D)  5 AU

Question 15

If the Sun is located at one focus of Earth's elliptical orbit,what is at the other focus?

Accepted Answer

A)  Earth 
B)  The Moon 
C)  Nothing 
D)  This is a trick question.An ellipse has only one focus. 
A)  Earth 
B)  The Moon 
C)  Nothing 
D)  This is a trick question.An ellipse has only one focus.

Question 16

According to Aristotle,what is the natural state of all objects? In practical terms,what does this mean for moving objects? How did Galileo disagree with Aristotle's theory?

Accepted Answer

According to Aristotle,the natural state

Question 17

Which of the following is true about a comet that is on an elliptical orbit around the Sun?

Accepted Answer

A)  The comet's speed is greatest when it is farthest from the Sun. 
B)  The comet's speed is greatest when it is nearest the Sun. 
C)  This comet's speed is zero. 
D)  The comet's speed is constant because its mass and the Sun's mass stay approximately the same. 
A)  The comet's speed is greatest when it is farthest from the Sun. 
B)  The comet's speed is greatest when it is nearest the Sun. 
C)  This comet's speed is zero. 
D)  The comet's speed is constant because its mass and the Sun's mass stay approximately the same.

Question 18

What factor did Newton add to Kepler's third law?

Accepted Answer

A)    
B)    
C)    
D)    
A)    
B)    
C)    
D)

Question 19

Johannes Kepler found that a planet's period was inversely proportional to the cube of its semimajor axis.

Accepted Answer

A) True 
 B)False

Question 20

If the distance between the Earth and Sun were cut in half,the gravitational force between these two objects would

Accepted Answer

A)  decrease by 4. 
B)  decrease by 2. 
C)  increase by 2. 
D)  increase by 4. 
A)  decrease by 4. 
B)  decrease by 2. 
C)  increase by 2. 
D)  increase by 4.

Exam 3: Gravity and Orbitsa Celestial Ballet

The average distance between a planet and the Sun is given by the __________ of its elliptical orbit.

If a satellite sent to Mars is designed to return a rock sample to Earth,how fast must the satellite be launched from its surface in order to escape Mars's gravity? For reference,Mars has a mass of and a radius of 2,400 km.

How much stronger is the gravitational force of the Sun on the Earth compared to the gravitational force of the Sun on Pluto? Note that Pluto's semimajor axis is 40 AU and its mass is 0.002 times the mass of the Earth.

If you found an exoplanet whose mass was the same as Jupiter's,but the planet orbited its star with a period of 2 years and a semimajor axis of 1 AU,what would be the mass of its star? For reference,Jupiter has a semimajor axis of 5.4 AU and an orbital period of 12 years.

An empirical science is one that is based on

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?

The time it takes a planet to complete one full orbital revolution is commonly known as its

Kepler's third law can be expressed mathematically as

Even though they move at faster average speeds,the outer planets in the Solar System have longer periods than the inner planets because they are so far from the Sun that their orbits are enormous.

When the geocentric model of the solar system did not match the observed positions of the planets,

In a period of three months,a planet travels 30,000 km with an average speed of 10.5 km/s.Some time later,the same planet travels 65,000 km in three months.How fast is the planet traveling at this later time? During which period is the planet closer to the Sun?

Astronauts feel "weightless" on the Moon.Using Newton's universal law of gravitation,explain why this statement is true or false and why astronauts experience this feeling.

Two rocks (call them S and T)are a distance of 50 km from one another.Rock S has 20 times the mass of rock T.Which rock will move faster if the only force involved is their mutual gravitational attraction?

If Jupiter has an orbital period of 12 years,what is its average distance from the Sun?

If the Sun is located at one focus of Earth's elliptical orbit,what is at the other focus?

According to Aristotle,what is the natural state of all objects? In practical terms,what does this mean for moving objects? How did Galileo disagree with Aristotle's theory?

Which of the following is true about a comet that is on an elliptical orbit around the Sun?

What factor did Newton add to Kepler's third law?

Johannes Kepler found that a planet's period was inversely proportional to the cube of its semimajor axis.

If the distance between the Earth and Sun were cut in half,the gravitational force between these two objects would

Why Learn Astronomy

Patterns in the Skymotions of Earth

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 Liquidthe Giant Planets

Gravity Is More Than Keplers Laws

Planetary Adornmentsmoons and Rings

Dwarf Planets and Small Solar System Bodies

Taking the Measure of Stars

A Run-Of-The-Mill G-Type Starour Sun

Star Formation and the Interstellar Medium

Stars in the Slow Lanelow-Mass Stellar Evolution

Live Fast,die Younghigh-Mass Stellar Evolution

Our Expanding Universe

Galaxies

The Milky Waya Normal Spiral Galaxy

Modern Cosmology

The Origin of Structure

Life

Filters