Deck 3: Gravity and Orbitsa Celestial Ballet

Question 1

As we move farther from the Sun,the circumferences of planetary orbits are larger and the speeds at which planets travel increase.

Answer 1

False

Question 2

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

Answer 2

True

Question 3

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

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.

Answer 3

Ptolemy added epicycles to the geocentric model to match the observed data.

Question 4

Johannes Kepler obtained accurate data on the positions of the planets in the sky over time,which Galileo used to prove that planets revolved around the Sun.

Question 5

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.

Question 6

Kepler's third law holds true mathematically only if the period is expressed in years and the semimajor axis is expressed in AU.

Question 7

The only acceleration you experience on a merry-go-round is when it starts or stops.

Question 8

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

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

Question 9

Once two objects are far enough away from each other,they no longer exert any gravitational attraction on each other.

Question 10

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

Question 11

Mass and weight are different names for the same physical property of matter.

Question 12

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

Question 13

When the Earth catches up to a slower moving outer planet and passes it in its orbit like a faster runner overtakes a slower runner in an outside lane,the planet

A) exhibits retrograde motion.
B) slows down because it feels the Earth's gravitational pull.
C) decreases in brightness as it passes through the Earth's shadow.
D) moves into a more elliptical orbit.

Question 14

Planets orbit the Sun on circular orbits.

Question 15

An unbound orbit results when a satellite has a velocity greater than the escape velocity.

Question 16

Planets with circular orbits travel at the same speed at all points in their orbits,whereas planets with elliptical orbits change their speeds at different points in their orbits.

Question 17

A planet travels fastest when it is closest to the Sun.

Question 18

A kilogram of lead has more mass than a kilogram of feathers.

Question 19

More massive objects fall faster in the Earth's gravitational field than less massive objects.

Question 20

An empirical science is one that is based on

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

Question 21

The force of gravity that an object has is directly related to its

A) inertia.
B) size.
C) mass.
D) density.

Question 22

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?

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

Question 23

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

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

Question 24

Suppose an asteroid had an orbit with a semimajor axis of 4 AU.How long would it take for it to orbit once around the Sun?

A) 2 years
B) 4 years
C) 8 years
D) 16 years

Question 25

If you travel 20 miles from home to school in 30 minutes,what is your average velocity?

A) 20 mph
B) 40 mph
C) 0.7 mph
D) 5 mph

Question 26

Kepler's third law can be expressed mathematically as

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

Question 27

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

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 28

The natural tendency of an object to resist changes in motion is called

A) inertia.
B) weight.
C) acceleration.
D) mass.

Question 29

You apply a force of 10 N to a grocery cart in order to get an acceleration of .If you apply a force of 20 N to the same grocery cart,its acceleration will be

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

Question 30

Which of the following properties of an astronaut changes when he/she is standing on the Moon,relative to when the astronaut is standing on Earth?

A) Weight
B) Mass
C) Inertia
D) All of the above

Question 31

If a 100-kg astronaut pushes on a 5,000-kg satellite and the satellite experiences an acceleration of ,what is the acceleration experienced by the astronaut in the opposite direction?

A)
B)
C)
D)

Question 32

Who of the following was NOT a proponent of the heliocentric model of the solar system?

A) Galileo
B) Copernicus
C) Newton
D) Ptolemy

Question 33

Kepler's third law is a relationship between an orbiting object's

A) gravitational force and mass.
B) acceleration and mass.
C) velocity and period.
D) period and semimajor axis.

Question 34

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

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.

Question 35

Newton's first law states that objects in motion

A) eventually come to rest.
B) experience an unbalanced force.
C) experience a nonzero acceleration.
D) stay in motion.

Question 36

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

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

Question 37

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

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

Question 38

__________ hypothesized that planetary motions could be explained by a force arising from the attraction between the mass of the planet and Sun that decreased with the square of the distance between them.

A) Johannes Kepler
B) Isaac Newton
C) Tycho Brahe
D) Nicholas Copernicus

Question 39

What is your acceleration if you go from 0 to 60 mph in 4 seconds?

A) 60 mph/s
B) 30 mph/s
C) 15 mph/s
D) 8.5 mph/s

Question 40

In a spaceship orbiting Earth,two astronauts want to measure the mass of a mouse.How can they easily do it if they are in constant free fall?

A) Place the mouse on a spring-loaded scale and weigh it.
B) Measure the gravitational attraction between the mouse and a steel ball of known mass.
C) Drop the mouse from the top of the shuttle to its bottom.
D) Push on the mouse with a known force and measure its acceleration.

Question 41

The Hubble Space Telescope orbits at an altitude of 600 km above the Earth's surface.Assuming it is in a stable circular orbit,what is its velocity? For reference,the Earth's radius is 6,400 km,and Earth's mass is .

A) 240,000 m/s
B) 7,500 m/s
C) 51,000 m/s
D) You must know the mass of the Hubble Space Telescope to determine its speed.

Question 42

What do we customarily call the semimajor axis of a circle? What is the value of the eccentricity of a circle? What would the value of the eccentricity be for a comet on a very elliptical orbit around the Sun?

Question 43

Suppose you are suddenly transported to a planet with 1/4 the radius of Earth but the same mass as the Earth.Your weight would __________ by a factor of __________.

A) increase;4
B) increase;16
C) decrease;4
D) decrease;16

Question 44

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 ,and the mass of the Sun is .

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

Question 45

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.

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 46

In terms of frames of reference,explain why an object moving in a straight line at constant speed remains in motion.

Question 47

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

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

Question 48

In the absence of air friction,a 0.001-kg piece of paper and a 0.1-kg notebook are dropped from the same height and allowed to fall to the ground.How do their accelerations compare?

A) The accelerations are the same.
B) The notebook's acceleration is 100 times faster than the paper's acceleration.
C) The notebook's acceleration is 1,000 times faster than the paper's acceleration.
D) The paper's acceleration is 100 times faster than the notebook's acceleration.

Question 49

What acceleration would result from a 5-N force acting on a 3-kg object? (A Newton [N] has units of kg . )

Question 50

Suppose you are suddenly transported to a planet with 1/4 the mass of Earth but the same radius as the Earth.Your weight would __________ by a factor of __________.

A) increase;4
B) increase;16
C) decrease;4
D) decrease;16

Question 51

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.

A)
B)
C)
D)

Question 52

Name the two ways in which an object's motion (meaning its velocity)can experience a nonzero acceleration.

Question 53

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

A) increase its orbital speed.
B) increase its weight.
C) decrease its weight.
D) decrease its orbital speed.

Question 54

If you weighed 150 lbs on Earth,what would you weigh on Mars? For reference,Mars has a mass that is 0.1 times the Earth's mass and Mars has a radius that is 0.5 times the Earth's radius.

A) 30 lbs
B) 110 lbs
C) 76 lbs
D) 60 lbs

Question 55

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?

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 56

Astronauts orbiting Earth in the space shuttle feel weightless in space because

A) they are farther away from the Earth.
B) they eat less food while in orbit.
C) the added gravitational pull of the Moon balances the Earth's gravitational pull.
D) they are in constant free fall around the Earth.

Question 57

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?

Question 58

Saturn has a semimajor axis of 9.6 AU.How long does it take Saturn to orbit once around the Sun?

Question 59

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?

Question 60

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

A)
B)
C)
D)

Question 61

Explain the difference between being weightless and being in free fall.

Question 62

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

Question 63

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.

Question 64

What information would you need to obtain about one of the moons of the planet Jupiter in order to measure the mass of Jupiter?

Question 65

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.

Question 66

You discover a moon orbiting a planet.The moon has an orbital period of 3 weeks,and the average distance between the moon and planet is .What is the planet's mass? Compare its mass to that of Jupiter,which is .

Question 67

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

Question 68

If a 100-kg asteroid collides with Earth,causing the asteroid to decelerate in one second from 1,000 m/s to 0 m/s,what acceleration will Earth experience according to Newton's third law? (Earth has a mass of approximately . )