Which statements accurately differentiate between dark matter and dark energy? Select the two correct answers.(1 point)

Question

Responses

Dark matter is black, while dark energy cannot be seen.
Dark matter is black, while dark energy cannot be seen.

There is much more dark matter in the universe, by mass.
There is much more dark matter in the universe, by mass.

There is much more dark energy in the universe, by mass.
There is much more dark energy in the universe, by mass.

Dark energy is the cause of the acceleration of the universe, while dark matter is the cause of the formation of structures.
Dark energy is the cause of the acceleration of the universe, while dark matter is the cause of the formation of structures.

Dark matter is the cause of the acceleration of the universe, while dark energy is the cause of the formation of structures.

Answer 1

The two correct statements that accurately differentiate between dark matter and dark energy are:

1. There is much more dark energy in the universe, by mass. (This is typically stated in terms of cosmic energy density, where dark energy constitutes about 68% of the universe's total energy content.)

2. Dark energy is the cause of the acceleration of the universe, while dark matter is the cause of the formation of structures. (Dark energy is believed to drive the accelerated expansion of the universe, whereas dark matter plays a crucial role in the formation of galaxies and large-scale structures.)

The other options are not accurate representations of the current understanding of dark matter and dark energy.

Answer 2

Which variables are involved in understanding Kepler's third law of motion?(1 point)
Responses

period of revolution, period of rotation
period of revolution, period of rotation

orbital velocity, distance to sun
orbital velocity, distance to sun

rotational velocity, distance to sun
rotational velocity, distance to sun

eccentricity of orbit, rotational velocity

Answer 3

The correct response involving the variables in understanding Kepler's third law of motion is:

period of revolution, period of rotation

However, it's important to note that Kepler's third law specifically relates the orbital period (period of revolution) of a planet to its average distance from the Sun, rather than directly involving the period of rotation or other variables mentioned in the unrevised answers. The law is commonly expressed as \( T^2 \propto a^3 \), where \( T \) is the period of revolution and \( a \) is the semi-major axis of the orbit.

If you are looking for the most closely related pair specifically in context to Kepler's laws, then:

• period of revolution, distance to sun is commonly more aligned with Kepler's Third Law, but this specific wording was not provided in your options.

Please keep that in mind when relating these concepts.

Answer 4

The geocentric model could not explain which of the following observations made by early astronomers? Select the two correct answers.(1 point)
Responses

The planets had epicycles.
The planets had epicycles.

Mars and Jupiter appeared to move backwards for some period of time.
Mars and Jupiter appeared to move backwards for some period of time.

Mercury and Venus changed in appearance throughout the year.
Mercury and Venus changed in appearance throughout the year.

The stars appeared to move.
The stars appeared to move.

Answer 5

The two correct answers regarding the observations that the geocentric model could not adequately explain are:

1. Mars and Jupiter appeared to move backwards for some period of time. (This phenomenon is known as retrograde motion, and the geocentric model struggled to explain how planets could appear to reverse their direction in the sky.)

2. Mercury and Venus changed in appearance throughout the year. (The geocentric model could not adequately explain the phases and varying brightness of these planets as observed from Earth.)

While the statement about the planets having epicycles refers to how the geocentric model attempted to explain planetary motion, it was not a failure of the model itself but rather part of its complex structure. Similarly, the observation that "the stars appeared to move" is standard in any model and thus not a clear failure of the geocentric model specifically.

Answer 6

A satellite orbiting Earth at an orbital radius r has a velocity v. What would the velocity be if the satellite is moved to an orbital radius of 6r?(1 point)
Responses

16√v
the fraction with numerator 1 and denominator square root of 6 v

16v
1 sixth v

6v
6 v

6–√v

Answer 7

To find the new velocity of a satellite when it is moved to an orbital radius of \(6r\), we can use the formula for the orbital velocity of a satellite, which is given by:

\[ v = \sqrt{\frac{GM}{r}} \]

Where \(G\) is the gravitational constant and \(M\) is the mass of the Earth.

If the satellite is moved to an orbital radius of \(6r\), we can express the new velocity \(v'\) as:

\[ v' = \sqrt{\frac{GM}{6r}} = \frac{1}{\sqrt{6}} \cdot \sqrt{\frac{GM}{r}} = \frac{1}{\sqrt{6}} \cdot v \]

Thus, the new velocity is:

\[ v' = \frac{v}{\sqrt{6}} \]

So the correct response is:

the fraction with numerator 1 and denominator square root of 6 v.

Answer 8

Which statements help explain how Earth formed as part of the solar system? Select the two correct answers.(1 point)
Responses

Very large asteroids broke apart to form rocky planets, including Earth.
Very large asteroids broke apart to form rocky planets, including Earth.

The accretion of cosmic dust formed the seeds of planets, including Earth.
The accretion of cosmic dust formed the seeds of planets, including Earth.

Water and ammonia condensed from gases to ice particles.
Water and ammonia condensed from gases to ice particles.

Gaseous planets slowly changed to rocky planets after colliding with meteorites.
Gaseous planets slowly changed to rocky planets after colliding with meteorites.

The denser rocky material in the solar nebula stayed closer to the sun.
The denser rocky material in the solar nebula stayed closer to the sun.

Answer 9

The two correct statements that help explain how Earth formed as part of the solar system are:

1. The accretion of cosmic dust formed the seeds of planets, including Earth. (This refers to the process where small particles of dust and gas in the solar nebula gradually clumped together to form larger bodies, ultimately leading to planet formation.)

2. The denser rocky material in the solar nebula stayed closer to the sun. (This is relevant to the formation of terrestrial planets, as the heat from the young Sun caused the lighter gases to be blown away, leaving the denser materials to form rocky planets like Earth in the inner solar system.)

The other statements either involve inaccuracies or misrepresent the processes involved in the formation of the solar system.