Astronomy Exam 2

What is the semi major axis of the Asteroid Camillo which has an orbital period of 1.67 years?

1.41 AU

When the spacecraft is halfway how does the strength on the probe by Earth compare with the strength of the probe by Mars?

1/10th F

What would the force be in terms of F if the mass M was doubled?

2F

Imagine a new planet in our solar system located 3 AU from the Sun. Which of the following best approximates the orbital period of this planet?

5 years

A planet with the same mass as Earth orbiting at a distance of 1 AU from a star with four times the Sun's mass.

6 months

The recently discovered Eris orbits the Sun every 557 years. What is its average distance (semimajor axis) from the Sun?

67.7 AU

Roughly how will Venus appear this night?

A

Which matches Earth's orbit?

A

During which part of orbit is planet moving with greatest speed?

A (biggest area)

Which person is weightless?

A child in the air as she plays on a trampoline.

Which best describes how a planet's mass will affect its orbital period?

A planet's mass does not affect its orbital period.

When we see Jupiter in retrograde motion, it means that

Earth is passing Jupiter in orbit, with both planets on the same side of the Sun

Kepler's first law states that the orbit of each planet is an ellipse with the Sun at one focus. Which of the following statements describe a characteristic of the solar system that is explained by Kepler's first law?

Earth is slightly closer to the Sun on one side of its orbit than on the other side. The Sun is located slightly off-center from the middle of each planet's orbit.

Earth is closer to the Sun in January than in July. Therefore, in accord with Kepler's second law:

Earth travels faster in its orbit around the Sun in January than in July.

You discover an asteroid that orbits the Sun with the same 1-year orbital period as Earth. Which of the following statements must be true?

The asteroid's average (semimajor axis) distance from the Sun is

Given that Earth is much larger and more massive than the Moon, how does the strength of the gravitational force that the Moon exerts on Earth compare to the gravitational force that Earth exerts on the Moon?

By Newton's third law, equal in force

Imagine the planet shown in moving counter clockwise. What direction is the planet's acceleration (change in the planet's motion) at the point shown? (planet at top of circle)

C (down)

Imagine the planet shown in moving counter clockwise. What direction is the planet's force at the point shown? (planet at top of circle)

C (down)

Which asteroid experiences the largest force from its partner asteroid? A. m=5 , d=1, m=3 B. m=3 , d=1, m=5 C. m=5 , d=1, m=5

C.

An adult and a child push off one another while standing on ice. How do their accelerations compare?

Child's acceleration is larger

While driving you hit an unfortunate bug. Which experiences a greater force, the bug or the windshield?

The bug and the windshield experience the same force

As a comet orbits around the Sun, its maximum speed is twice its minimum speed. What can we say about its orbit?

The comet is twice as far from the Sun at aphelion as at perihelion.

In Part A, you found that your weight will be greater than normal when the elevator is moving upward with increasing speed. For which of the following other motions would your weight also be greater than your normal weight?

The elevator moves downward while slowing in speed.

Three pairs of asteroids are shown in the figure. By Newton's laws how does the amount of force of gravity exerted on the larger asteroid of A compare to the smaller asteroid of A? A. m=4, d=10, m=1 B. m=2, d=10, m=2 C. m=4, d=10, m=2

The forces are equal on each other.

Which of the following is not considered a potential solution to the question of why we lack any evidence of a galactic civilization?

The galactic civilization is undetectable because they operate under different laws of physics from the ones we know

A hockey puck is gliding along a sheet of ice at a constant velocity (assume that friction and air resistance are small enough to ignore). What can you say about the net force / total force on the hockey puck?

The net force is zero

In the Greek geocentric model, the retrograde motion of a planet occurs when:

The planet actually goes backward in its orbit around Earth.

Which statement correctly describes the way the planet sizes are shown compared to their orbits?

The planets are all much too large compared to their orbits.

What defines the habitable zone around a star?

The region around a star where liquid water can exist on planetary surfaces

An adult and a child push off one another while standing on ice. The amount of force exerted by the adult on the child is

The same has the force of the child on the adult

Which of the following orbits has the largest semimajor axis?

The semimajor axis is half of the distance across the ellipse in its longest direction (which means half of the major axis), which is also the planet's average distance from the Sun. Therefore, the ellipse that measures the longest across is the one with the largest semimajor axis.

Why did the Greeks conclude that the Earth was stationary, and that the Sun and the planets orbited around the Earth?

They did not observe any change in the separation of stars during Earth's orbit.

If a small weather satellite and the large International Space Station are orbiting Earth at the same altitude above Earth's surface, which object takes longer to orbit once around Earth?

They would take the same amount of time

Imagine a spacecraft traveling from the Earth to the Moon. Point B is exactly halfway between Earth and the Moon. In what direction would the net / total force point if the spacecraft is moving towards the moon at Point B?

Towards the Earth

In Ptolemy's Earth-centered model for the solar system, Venus always stays close to the Sun in the sky and, because it always stays between Earth and the Sun, its phases range only between new and crescent. The following statements are all true and were all observed by Galileo. Which one provides evidence that Venus orbits the Sun and not Earth?

We sometimes see gibbous (nearly but not quite full) Venus.

The Sun exerts a gravitational force on Earth. Does Earth exert a force on the Sun?

Yes, and the force is the same strength as the force of the Sun on Earth

Imagine an orbit that is a perfect circle as shown. The time between each position shown is exactly one month. Does this planet obey Kepler's second?

Yes, equal times and equal area

Suppose you are in an elevator car when the elevator cable breaks. Which of the following correctly describes what happens and why.

You float weightlessly within the elevator car because you and the elevator both begin to accelerate downward at the same rate.

To make a rocket turn left, you need to:

fire an engine that shoots out gas to the right.

In Ptolemy's Earth-centered model for the solar system, Venus's phase is never full as viewed from Earth because it always lies between Earth and the Sun. In reality, as Galileo first recognized, Venus is __________.

full whenever it is on the opposite side of the Sun from Earth

Based on the video, which Venus phase would be impossible to see (from Earth) if Venus orbited Earth as described in Ptolemy's Earth-centered model? Based on the video, which Venus phase would be impossible to see (from Earth) if Venus orbited Earth as described in Ptolemy's Earth-centered model?

gibbous (nearly full)

A car is accelerating when it is

going around a circular track at a steady 100 miles per hour.

Suppose you are in an elevator. As the elevator starts upward, its speed will increase. During this time when the elevator is moving upward with increasing speed, your weight will be __________.

greater than your normal weight at rest

When we say that a planet has a highly eccentric orbit, we mean that:

in some parts of its orbit it is much closer to the Sun than in other parts.

We never see a crescent Jupiter from Earth because Jupiter __________.

is farther than Earth from the Sun

Is a parsec a unit of length or a unit of angle?

length

Your weight on Earth is the gravitational force exerted on you by the Earth. Would your weight be more, less, or the same on the Moon?

less

A planet is discovered orbiting the star 51 Peg with a period of four days (0.01 years). 51 Peg has the same mass as the Sun. Mercury's orbital period is 0.24 years, and Venus's is 0.62 years. The average orbital radius of this planet is

less than Mercury's.

Suppose you are in an elevator that is moving upward. As the elevator nears the floor at which you will get off, its speed slows down. During this time when the elevator is moving upward with decreasing speed, your weight will be __________.

less than your normal weight at rest

Galileo's contribution to astronomy included:

making observations and conducting experiments that dispelled scientific objections to the Sun-centered model.

Compared to their values on Earth, on another planet your

mass would be the same but your weight would be different.

Galileo's discovery of moons in Jupiter showed people who argued against the Copernicus model that

moons could orbit moving planets

A person stands on a scale in an elevator. When the elevator is stopped, they weight 180 lbs. When the elevator is accelerating up, their weight is

more

The Moon takes roughly 28 days to complete one orbit around Earth. If the orbital radius of the Moon were twice its actual value, its orbital period would be

more than 56 days.

Which of the following describes how a planet's orbital period will change when its distance is doubled?

more than double

A planet is moving in prograde motion. Over the course of 1 night it will appear to

move from east to west

A planet is moving in retrograde motion. Over the course of one night, it will appear to

move from east to west

A planet is moving in retrograde motion. Over the course of several nights, it will appear to

move from east to west

A planet is moving in normal (prograde) motion. Over the course of several nights, it will appear to

move from west to east

A planet is moving in prograde motion. Over the course of several nights, it will appear to

move from west to east

If the spaceprobe lost all ability to control its motion and was at rest at the midpoint, would it stay or start to move?

move towards Earth, speed up, increase, greatest acceleration right before impact on surface of Earth

In Ptolemy's Earth-centered model, when would Venus appear directly behind the Sun as viewed from Earth?

never

When would you expect to see Venus high in the sky at midnight?

never

Where would you look to see a planet rise when it's undergoing apparent retrograde motion?

on the eastern horizon

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

The reason an astronaut on the International Space Station feels weightless is that

the astronaut is falling along with the Station

When you are standing on a scale in an elevator, what exactly does the scale measure?

the force you exert on the scale

Consider the hypothetical observation "a planet beyond Saturn rises in west, sets in east." This observation is not consistent with a Sun-centered model, because in this model __________.

the rise and set of all objects depends only on Earth's rotation

A person stands on a scale in an elevator. When the elevator is stopped, they weight 180 lbs. When the elevator is accelerating up, their mass is

the same

Consider a planet orbiting the Sun. If the mass of the planet doubled but the planet stayed at the same orbital distance, then the planet would take

the same amount of time to orbit the Sun

According to Kepler's third law:

Jupiter orbits the Sun at a faster speed than Saturn.

All of the following statements are true. Which one can be explained by Kepler's second law?

Mars moves faster in its orbit when it is closer to the Sun than when it is farther from the Sun.

A planet with twice Earth's mass orbiting at a distance of 1 AU from a star with the same mass as the Sun.

1 year

Imagine that Venus is in its full phase today. If we could see it, at what time would the full Venus be highest in the sky?

at noon

When would a new Venus be highest in the sky?

at noon

Jupiter orbits the Sun at an average distance of 5.203AU and takes 11.86years to complete each orbit. Based on these facts, which statement is true?

(11.86)^2=(5.203)^3

If the parallax angle for star A is 1 arcsecond, what is the distance from the Sun to that star?

1 parsec

Imagine the planet shown in moving counter clockwise. What direction is the planet's velocity at the point shown? (planet at right of circle)

A. ^

A spacecraft is traveling from the Earth to the Moon. Point B is exactly halfway between Earth and the Moon. At what point is the gravitational force on the spacecraft from the Earth the greatest?

A. closer to Earth

Each of the four diagrams below represents the orbit of the same comet, but each one shows the comet passing through a different segment of its orbit around the Sun. During each segment, a line drawn from the Sun to the comet sweeps out a triangular-shaped, shaded area. Assume that all the shaded regions have exactly the same area. Rank the segments of the comet's orbit from left to right based on the length of time it takes the comet to move from Point 1 to Point 2, from longest to shortest. If you think that two (or more) of the diagrams should be ranked as equal, drag one on top of the other(s) to show this equality.

Although Kepler wrote his laws specifically to describe the orbits of the planets around the Sun, they apply more generally. Kepler's second law tells us that as an object moves around its orbit, it sweeps out equal areas in equal times. Because all the areas shown here are equal, the time it takes the comet to travel each segment must also be the same.

Why do the planets orbit the Sun (i.e. why don't they crash into the Sun)?

Although the planets experience a force of gravity from the Sun, since they are moving, their trajectories bend around the Sun rather than lead directly into the Sun.

Which of the following orbits shows the planet at aphelion?

Aphelion is the point in a planet's orbit that is farthest from the Sun.

In a heliocentric model, which letter corresponds to this phase of Venus?

B

Which segment of the planet's orbit would take the same amount of time as segment A?

B

In a geocentric model where do you see "new" phase of Venus?

Both A and C

To find exoplanets, Kepler must monitor a large number of stars because

Both B and C B. only a small percentage of systems have the correct geometry for transits to be observed C. planets will only be transiting the star from a small percentage of the time

Earth is slightly closer to the Sun in January than in July. How does the area swept out by Earth's orbit around the Sun during the 31 days of January compare to the area swept out during the 31 days of July?

Both areas are the same.

Which asteroid exerts a greater gravitational force on the other? m=5 , d=5, m=3

Both exert forces of the same strength

Suppose two comets, comet A and comet B, were orbiting the Sun, having the same average orbital radii. If comet A had a higher eccentricity than comet B, which comet would, during some portion of its orbit, have the highest orbital speed?

Comet A.

Consider the statement "There's no gravity in space." This statement is:

Completely false.

Imagine an orbit that is a perfect circle as shown. The time between each position shown is exactly one month. If you were watching this planet for the entire orbit how would its speed be behaving?

Constant

A boy is spinning a rock tied to a rope horizontally above his head. In which direction will the rock go if the string breaks?

D. (straight / direction of motion)

Imagine the planet shown in moving counter clockwise. What direction is the planet's velocity at the point shown? (planet at top of circle)

D. <---

Consider again the set of observations from Part A. This time, classify each observation according to whether it is consistent with only the Earth-centered model, only the Sun-centered model, both models, or neither model. (Note that an observation is "consistent" with a model if that model offers a simple explanation for the observation.)

Earth-centered only a planet beyond Saturn rises in west, sets in east Sun-centered only positions of nearby stars shift slightly back and forth each year Mercury goes through a full cycle of phases Both models Moon rises in east, sets in west a distant galaxy rises in east, sets in west each day stars circle daily around north or south celestial pole Neither model we sometimes see a crescent Jupiter

A car traveling West slams on its brakes and comes to a stop. In which direction was its acceleration?

East

If a planet were moving with retrograde motion how would the planet appear to move across the sky in a single night? Where would it rise, where would it set?

East to West, rise in the East and set in the West

Which of the following orbits is the most eccentric?

Eccentricity is a measure of how "stretched out" an ellipse is. A perfect circle has zero eccentricity, and the most stretched out ellipse has the largest eccentricity.

What shape has the largest eccentricity?

Elongated oval

The recently discovered Eris orbits the Sun every 557 years. How does its average distance compare to that of Pluto?

Eris orbits farther than Pluto. Submit

What would the force be in terms of F if the distance r was doubled?

F/4

Consider again the diagrams from Parts A and B, which are repeated here. Again, assume that all the shaded areas have exactly the same area. This time, rank the segments of the comet's orbit based on the speed with which the comet moves when traveling from Point 1 to Point 2, from fastest to slowest. If you think that two (or more) of the diagrams should be ranked as equal, drag one on top of the other(s) to show this equality.

From Parts A and B, you know that the comet takes the same time to cover each of the four segments shown, but that it travels greater distances in the segments that are closer to the Sun. Therefore, its speed must also be faster when it is closer to the Sun. In other words, the fact that that the comet sweeps out equal areas in equal times implies that its orbital speed is faster when it is nearer to the Sun and slower when it is farther away.

If the spacecraft is moving towards the moon at Point B but not firing any jets or rockets, what is happening to its speed?

It is slowing down

If an astronomer claims to have discovered an object with a very eccentric orbit, which of the following best describes the orbital trajectory of the object?

It looks like a very squashed oval.

Which of the following was not a major advantage of Copernicus's Sun-centered model over the Ptolemaic model?

It made significantly better predictions of planetary positions in our sky. Submit

Consider again the diagrams from Parts D and E, which are repeated here. Again, imagine that you observed the asteroid as it traveled for one week, starting from each of the positions shown. This time, rank the positions (A-D) from left to right based on how fast the asteroid is moving at each position, from fastest to slowest. If you think that two (or more) of the diagrams should be ranked as equal, drag one on top of the other(s) to show this equality.

Just as you found for the comet in Parts A through C, the asteroid must be traveling at a higher speed during parts of its orbit in which it is closer to the Sun than during parts of its orbit in which it is farther away. You should now see the essence of Kepler's second law: Although the precise mathematical statement tells us that an object sweeps out equal areas in equal times, the key meaning lies in the idea that an object's orbital speed is faster when nearer to the Sun and slower when farther away. This idea explains why, for example, Earth moves faster in its orbit when it is near perihelion (its closest point to the Sun) in January than it does near aphelion (its farthest point from the Sun) in July.

Which of the following paths could not be a real orbit for a planet around the Sun?

Kepler's first law tells us that the orbit of a planet must be an ellipse with the Sun at one focus. Therefore, the path that shows the Sun in the center of the ellipse, rather than at a focus, cannot be the real orbital path of a planet. (Note that the circular path is allowed because a circle is an ellipse in which both foci are at the center.)

Each of the four diagrams below represents the orbit of the same asteroid, but each one shows it in a different position along its orbit of the Sun. Imagine that you observed the asteroid as it traveled for one week, starting from each of the positions shown. Rank the positions based on the area that would be swept out by a line drawn between the Sun and the asteroid during the one-week period, from largest to smallest. If you think that two (or more) of the diagrams should be ranked as equal, drag one on top of the other(s) to show this equality.

Kepler's second law tells us that the asteroid will sweep out equal areas in equal time intervals. Therefore, the area swept out in any one week period must always be the same, regardless of the asteroid's location in its orbit around the Sun.

Consider again the diagrams from Part A, which are repeated here. Again, assume that all the shaded areas have exactly the same area. This time, rank the segments of the comet's orbit from left to right based on the distance the comet travels when moving from Point 1 to Point 2, from longest to shortest. If you think that two (or more) of the diagrams should be ranked as equal, drag one on top of the other(s) to show this equality.

Kepler's second law tells us that the comet sweeps out equal areas in equal times. Because the area triangle is shorter and squatter for the segments nearer to the Sun, the distance must be greater for these segments in order for all the areas to be the same.

Consider again the diagrams from Part D, which are repeated here. Again, imagine that you observed the asteroid as it traveled for one week, starting from each of the positions shown. This time, rank the positions from left to right based on the distance the asteroid will travel during a one-week period when passing through each location, from longest to shortest. If you think that two (or more) of the diagrams should be ranked as equal, drag one on top of the other(s) to show this equality.

Notice the similarity between what you have found here and what you found for the comet in Part B. Kepler's second law tells us any object will sweep out equal areas in equal times as it orbits the Sun, which means the area triangles are shorter and squatter when the object is nearer to the Sun, so that the object covers a greater distance during any particular time period when it is closer to the Sun than when it is farther away.

During how many potions of the planet's orbit would the planet be speeding up for the entire time?

Only 1 portion

Two planets are observed going around a star. Planet Xoron has an orbital period that is twice as long as planet Krypton. Which planet has a shorter average orbital radius?

Planet Krypton

Kepler's second law states that as a planet orbits the Sun, it sweeps out equal areas in equal times. Which of the following statements describe a characteristic of the solar system that is explained by Kepler's second law?

Pluto moves faster when it is closer to the Sun than when it is farther from the Sun.

You observe 2 stars over the course of a year and find that both stars have measurable parallax. 1 arcsecond is equal to 1/3600 degree. Star X is 1 arcsecond and Star Y is 1/2 arcsecond. Which is closer?

Star X

Consider the following observations. Classify each observation based on whether it is a real observation (a true statement of something we can actually see from Earth) or one that is not real (a statement of something that does not really occur as seen from Earth).

TRUE Moon rises in east, sets in west a distant galaxy rises in east, sets in west each day stars circle daily around north or south celestial pole positions of nearby stars shift slightly back and forth each year Mercury goes through a full cycle of phases FALSE a planet beyond Saturn rises in west, sets in east we sometimes see a crescent Jupiter

The Copernican model wasn't perfect. Which of the following was something Copernicus didn't get right based on what we know today?

That all planets move in perfect circles

All of the following statements are true. Which one can be explained by Kepler's third law?

Venus orbits the Sun at a faster orbital speed than Earth.

Kepler's third law states that a planet's orbital period, p, is related to its average (semimajor axis) orbital distance, a, according to the mathematical relationship p2=a3p2=a3. Which of the following statements describe a characteristic of the solar system that is explained by Kepler's third law?

Venus orbits the Sun faster than Earth orbits the Sun. Inner planets orbit the Sun at higher speed than outer planets.

Which of the following can you observe about Venus with the naked eye? Select all that apply.

Venus sometimes shines brightly in the western sky shortly after sunset Venus sometimes shines brightly in the eastern sky shortly before dawn

In Fullerton what are the sky coordinates of Polaris, the North Star?

altitude 34, azimuth 0

Tycho Brache's greatest contribution to astronomy was

collecting data for Kepler

Tycho Brahe's contribution to astronomy included:

collecting data that enabled Kepler to discover the laws of planetary motion. Submit

Suppose an object is moving in a straight line at 50 mph. According to Newton's First Law of motion, the object will

continue to move in the same way until it is acted upon by a force

How would the strength of the force between the Moon and Earth change if the mass of the Moon were somehow made of two times greater than its actual mass?

doubles mass -> doubles Force (2F)

Your weight on Earth is the force between you and the Earth. Would you weigh more, less or the same on Mars?

weigh less

If Earth's orbit were very eccentric, but the average distance from the Sun were still 1 AU, its orbital period

would still be one year.