Astr 1030 Chapter 4
Which person is weightless? A - A child in the air as she plays on a trampoline. B - A scuba diver exploring a deep-sea wreck C - An astronaut on the moon
A - A child in the air as she plays on a trampoline
Consider the statement "There's no gravity in space." This statement is: A - Completely false. B- False if you are close to a planet or moon, but true in between the planets. C - Completely true
A - Completely false
Choose the correct definition and two examples of kinetic energy: A - Kinetic energy is the energy an object has due to its motion. Two examples are a car driving down the highway or the movements of the molecules of liquid in a cup of hot coffee. B - Kinetic energy is the energy an object has due to its position. Two examples are a car resting on the hill or the movements of the molecules of liquid in a cup of hot coffee. C - Kinetic energy is the energy an object has due to its motion. Two examples are a car resting on the hill or the movements of the molecules of liquid in a cup of hot coffee. D - Kinetic energy is the energy an object has due to its position. Two examples are a car driving down the highway or the movements of the molecules of liquid in a cup of hot coffee.
A - Kinetic energy is the energy an object has due to its motion. Two examples are a car driving down the highway or the movements of the molecules of liquid in a cup of hot coffee.
Earth has two tidal bulges at all times. Approximately where are these bulges located? A - One faces the Moon and one faces opposite the Moon. B - One is over the Atlantic Ocean, and one is over the Pacific Ocean. C - One faces the Moon and one faces the Sun. D - Both are on lines perpendicular to the Earth-Moon line.
A - One faces the Moon and one faces opposite the Moon
Choose the correct definition and two examples of radiative energy. A - Radiative energy is energy in light. Sunlight carries this form of energy, as do other forms of light including X-rays and radio waves. B - Radiative energy is energy of oscillation. Sunlight carries this form of energy, as do other forms of light including X-rays and acoustic waves. C - Radiative energy is energy of oscillation. Sunlight carries this form of energy, as do other forms of light including X-rays and radio waves. D - Radiative energy is energy in light. Sunlight carries this form of energy, as do other forms of light including X-rays and acoustic waves.
A - Radiative energy is energy in light. Sunlight carries this form of energy, as do other forms of light including x-rays and radio waves.
Suppose you lived on the Moon. Which of the following would be true? A - Your weight would be less than your weight on Earth, but your mass would be the same as it is on Earth. B - Both your weight and your mass would be the same as they are on Earth. C - Both your weight and your mass would be less than they are on Earth. D - Your mass would be less than your mass on Earth, but your weight would be the same as it is on Earth.
A - Your weight would be less than your weight on Earth, but your mass would be the same as it is on Earth.
If the Moon were closer to Earth, high tides would: A - Be higher than they are now B - Be lower than they are now C - Occur three or more times a day rather than twice a day
A - be higher than they are now
Compared to its angular momentum when it is farthest from the sun, Earth's angular momentum when it is nearest to the Sun is: A - the same B - less C - greater
A - the same
the planets never travel in a straight line as they orbit the Sun. According to Newton's second law of motion, this must mean that _______.
A force is acting on the planets
chemical potential
An apple contains ________ energy that your body can convert into other forms energy.
gravitational potential
An asteroid that is moving farther from the Sun is gaining ________ energy.
two high tides and two low tides each day
Any particular location on Earth experiences __________.
One faces the Moon, and one faces opposite the Moon.
As shown in the animation, Earth has two tidal bulges at all times. Approximately where are these bulges located?
(Blank 1) gradually becomes stronger (Blank 2) the strength of gravity follows an inverse square law with distance
As the cloud collapses, the force of gravity drawing the cloud inward __________ because __________.
(Blank 1) increases (Blank 2) gravitational potential energy being converted to thermal energy
As the cloud shrinks in size, its central temperature __________ as a result of __________.
Part C As the cloud shrinks in size, its central temperature __________ as a result of __________. - increases - gravitational potential energy being converted to thermal energy
As the cloud shrinks in size, its gravitational potential energy decreases. Because energy cannot simply disappear, the "lost" gravitational potential energy must be converted into some other form. Some of it is converted into thermal energy, which raises the temperature of the gas cloud. The rest is mostly converted into radiative energy, which is released into space as light.
(Blank 1) speeds up (Blank 2) its total angular momentum is conserved
As the cloud shrinks in size, its rate of rotation __________ because __________.
High tides are highest at both full moon and new moon. Low tides are lowest at both full moon and new moon.
As you watch the animation, notice that the size of the tidal bulges varies with the Moon's phase, which depends on its orbital position relative to the Sun. Which of the following statement(s) accurately describe(s) this variation?
You have found that tides on Earth are determined primarily by the position of the Moon, with the Sun playing only a secondary role. Why does the Moon play a greater role in causing tides than the Sun? A - because the gravitational force between Earth and the Moon is stronger than the gravitational force between Earth and the Sun B - because the gravitational attraction between Earth and the Moon varies more across Earth than does the gravitational attraction between Earth and the Sun C - because the Moon orbits Earth faster than Earth orbits the Sun
B - Because the gravitational attraction between Earth and the Moon varies more across Earth than does the gravitational attraction between Earth and the Sun
If you want to make a rocket turn left, you need to: A - Fire an engine that shoots out gas to the left B - Fire an engine that shoots out gas to the right C - Spin the rocket clockwise.
B - Fire an engine that shoots out gas to the right.
When a spinning ice skater pulls in his arms, he spins faster because _________. A - there is less friction with the ice B - his angular momentum must be conserved, so reducing his radius must increase his speed of rotation C - there exists an unbalanced reaction force D - there is less friction with the air
B - His angular momentum must be conserved, so reducing his radius must increase his speed of rotation.
Why is Newton's version of Kepler's third law so useful to astronomers? A - It tells us that more-distant planets orbit the Sun more slowly. B - It can be used to determine the masses of many distant objects. C - It explains why objects spin faster when they shrink in size. D - It allows us to calculate distances to distant objects.
B - It can be used to determine the masses of many distant objects
Any particular location on Earth experiences ____________. A - two sets of high and low tides in the ocean, but only one set on land B - two high tides and two low tides each day C - one high tide and one low tide each month D - two high tides and two low tides each month E - one high tide and one low tide each day
B - Two high tides and two low tides each day
Which of the following statements is NOT one of Newton's Laws of Motion? A - For any force, there always is an equal and opposite reaction force. B - What goes up must come down. C - In the absence of a net force acting upon it, an object moves with constant velocity. D - The rate of change of momentum of an object is equal to the net force applied to the object.
B - What goes up must come down.
Most people are familiar with the rise and fall of ocean tides. Do tides also affect land? A - No, tides only affect the oceans. B - Yes, though land rises and falls by a much smaller amount than the oceans. C - No, tides can only affect liquids and gases, not solids. D - Yes, land rises and falls with tides equally as high (and low) as the oceans.
B - Yes, though land rises and falls by a much smaller amount than the oceans
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 __________. A - less than your normal weight at rest B - greater than your normal weight at rest C - equal to your normal weight at rest
B - greater than your normal weight at rest
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 __________. (Be sure to note that the video does not show a situation in which the elevator is slowing while moving upward, so you will need to decide which portion of the video is relevant to this situation; Hint 1 may be helpful.) A - equal to your normal weight at rest B - less than your normal weight at rest C - greater than your normal weight at rest
B - less than your normal weight at rest
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 __________. A - the Moon and Earth both have equal accelerations, because the forces are equal B - the Moon has a larger acceleration than Earth, because it has a smaller mass C - Earth has a larger acceleration than the Moon, because it has a larger mass
B - the Moon has a larger acceleration than Earth, because it has a smaller mass
When you are standing on a scale in an elevator, what exactly does the scale measure? A - your mass B - the force you exert on the scale C - the gravitational force exerted on you by Earth
B - the force you exert on the scale
Suppose that two objects collide. Which of the following things is NOT the same both before and after the collision? A - the total energy of the objects B - the total temperature of the objects C - the total angular momentum of the objects D - the total momentum of the objects
B - the total temperature of the objects
Suppose that the Sun were to collapse from its current radius of about 700,000 km to a radius of only about 6000 km (about the radius of Earth). What would you expect to happen as a result? A - Both the total amount of energy and the rotation rate would remain the same. B - The Sun would gain more energy and more angular momentum. C - A tremendous amount of gravitational potential energy would be converted into other forms of energy, and the Sun would spin much more rapidly. D - A tremendous amount of gravitational potential energy would be converted into other forms of energy, and the Sun would spin much more slowly.
C - A tremendous amount of gravitational potential energy would be converted into other forms of energy, and the Sun would spin much more rapidly.
According the the law of universal gravitation, what would happen to Earth if the Sun were somehow replaced by a black hole of the same mass? A - Earth would quickly be sucked into the black hole B - Earth would slowly spiral in to the black hole' c - Earth's orbit would not change
C - Earth's orbit would not change
Suppose that two asteroids are orbiting the Sun on nearly identical orbits, and they happen to pass close enough to each other to have their orbits altered by this gravitational encounter. If one of the asteroids ends up moving to an orbit that is closer to the Sun, what happens to the other asteroid? A - It will become much cooler. B - It will also end up on an orbit that is closer to the Sun. C - It will end up on an orbit that is farther from the Sun. D - It will stay on its original orbit.
C - It will end up on an orbit that is farther from the sun
One tidal bulge faces toward the Moon because that is where the gravitational attraction between Earth and the Moon is strongest. Which of the following best explains why there is also a second tidal bulge? A - The second tidal bulge is a rebound effect, created when water on the side facing the Moon falls back down and thereby pushes up the water on the opposite side of Earth. B - The second tidal bulge is created by the centrifugal force caused by Earth's rapid rotation. C - The second tidal bulge arises because gravity weakens with distance, essentially stretching Earth along the Earth-Moon line. D - The second tidal bulge is created by the Sun's gravity.
C - The second tidal bulge arises because gravity weakens with distance, essentially stretching Earth along the Earth-Moon line.
If Earth were twice as far from the Sun, the force of gravity attracting Earth to the Sun would be: A - twice as strong B - half as strong C - one-quarter as strong
C - one-quarter as strong
What does temperature mean? A - the average mass of particles in a substance B - the total amount of heat in a substance C - the average kinetic energy of particles in a substance D - the total potential energy of particles in a substance
C - the average kinetic energy of particles in a substance
The acceleration of gravity on Earth is approximately 10 m/s2 (more precisely, 9.8 m/s2). If you drop a rock from a tall building, about how fast will it be falling after 3 seconds? A- 20 m/s B- 30 m/s^2 C- 30 m/s D- 10 m/s E- 10 m/s^2
C- 30 m/s
the Moon has a larger acceleration than Earth, because it has a smaller mass
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 __________.
Completely false.
Consider the statement "There's no gravity in space." This statement is:
According to the universal law of gravitation, if you triple the distance between two objects, then the gravitational force between them ________. A -- increases by a factor of 9 B - increases by a factor of 3 C - decreases by a factor of 3 D - decreases by a factor of 9
D - Decreases by a factor of 9
Choose the correct definition and two examples of potential energy. A - Potential energy is energy of close molecules interaction. Two examples of potential energy are breakfast cereal, which has chemical potential energy, and a heavy book on the top shelf at the library, which has gravitational potential energy. B - Potential energy is energy of close molecules interaction. Two examples of potential energy are molecules of liquid in a cup of hot coffee, and a heavy book on the top shelf at the library, which has gravitational potential energy. C- Potential energy is energy that is stored. Two examples of potential energy are molecules of liquid in a cup of hot coffee, and a heavy book on the top shelf at the library, which has gravitational potential energy. D - Potential energy is energy that is stored. Two examples of potential energy are breakfast cereal, which has chemical potential energy, and a heavy book on the top shelf at the library, which has gravitational potential energy.
D - Potential energy is energy that is stored. Two examples of potential energy are breakfast cereal, which has chemical potential energy, and a heavy book on the top shelf at the library, which has gravitational potential energy.
Which of the following examples describes a situation where a car is experiencing a net force? A - The car is floating on a stationary boat. B - The car is moving at constant speed. C - The car is stopped on a hill D - The car is making a gradual turn.
D - The car is making a gradual turn
thermal
Due to its much higher density, water heated to 80 degrees (Celsius) contains more ________ energy than air at the same temperature.
one-quarter as strong.
If Earth were twice as far from the Sun, the force of gravity attracting Earth to the Sun would be:
be higher than they are now.
If the Moon were closer to Earth, high tides would:
Fire an engine that shoots out gas to the right.
If you want to make a rocket turn left, you need to:
Yes, though land rises and falls by a much smaller amount than the oceans.
Most people are familiar with the rise and fall of ocean tides, but do tides also affect land?
mass-
Nuclear fusion in stars converts some of the ________ energy of hydrogen nuclei into light and heat.
The second tidal bulge arises because gravity weakens with distance, essentially stretching Earth along the Earth-Moon line.
One tidal bulge faces toward the Moon because that is where the gravitational attraction between Earth and the Moon is strongest. Which of the following best explains why there is also a second tidal bulge?
kinetic
Rapidly moving comets have more ________ energy than slowly moving ones.
A tremendous amount of gravitational potential energy would be converted into other forms of energy and the Sun would spin much more rapidly.
Suppose that the Sun were to collapse from its current radius of about 700,000 km to a radius of only about 6000 km (about the radius of Earth). What would you expect to happen as a result?
It will end up on an orbit that is farther from the Sun.
Suppose that two asteroids are orbiting the Sun on nearly identical orbits, and they happen to pass close enough to each other to have their orbits altered by this gravitational encounter. If one of the asteroids ends up moving to an orbit that is closer to the Sun, what happens to the other asteroid?
Your mass would be the same as on Earth, but your weight would be different.
Suppose you visit another planet:
Suppose the Sun were suddenly to shrink in size but that its mass remained the same. According to the law of conservation of angular momentum, what would happen?
The Sun would rotate faster than it does now
Part D Suppose that the Sun were to collapse from its current radius of about 700,000 km to a radius of only about 6000 km (about the radius of Earth). What would you expect to happen as a result? - A tremendous amount of gravitational potential energy would be converted into other forms of energy and the Sun would spin much more rapidly.
The dramatic shrinkage of the Sun would mean the loss of a huge amount of gravitational potential energy. Because energy is always conserved, this "lost" gravitational potential energy must reappear in other forms, such as heat (thermal energy) and light (radiative energy). Meanwhile, conservation of angular momentum would ensure that the collapsed Sun would spin much faster.
Part A The animation shows a collapsing cloud of interstellar gas. As the cloud collapses, the force of gravity drawing the cloud inward __________ because __________. - gradually becomes stronger - the strength of gravity follows an inverse square law with distance
The force of gravity between any two particles increases as the particles come closer together. Therefore, as the cloud shrinks and particles move closer together, the force of gravity strengthens. This will tend to accelerate the collapse as long as no other force resists it—which is the case during the early stages of the collapse before the internal gas pressure builds up. (Once the gas pressure builds up, the outward push of the pressure can counteract the inward pull of gravity, which is why the cloud eventually stops contracting.)
radiative
The light from Polaris travels through space in the form of ________ energy.
Part B As the cloud shrinks in size, its rate of rotation __________ because __________. - speeds up - its total angular momentum is conserved
Total angular momentum is always conserved. In this case, because nothing is carrying angular momentum into or out of the cloud, the cloud's angular momentum stays constant. Maintaining constant angular momentum as the cloud shrinks requires that its rate of rotation increase, because angular momentum depends on the product of rotation rate and radius.
Part E Suppose that two asteroids are orbiting the Sun on nearly identical orbits, and they happen to pass close enough to each other to have their orbits altered by this gravitational encounter. If one of the asteroids ends up moving to an orbit that is closer to the Sun, what happens to the other asteroid? - It will end up on an orbit that is farther from the Sun.
Total energy must be conserved, so if one asteroid loses energy and moves to a closer orbit, the other must gain energy and move to a more distant orbit.
Because the gravitational attraction between Earth and the Moon varies more across Earth than does the gravitational attraction between Earth and the Sun
You have found that tides on Earth are determined primarily by the position of the Moon, with the Sun playing only a secondary role. Why does the Moon play a greater role in causing tides than the Sun?
A net force acting on an object will always cause a change in the object's _________.
momentum
Suppose you kick a soccer ball straight up to a height of 10 meters. Which of the following is true about the gravitational potential energy of the ball during its flight?
the ball's gravitational potential energy is greatest at the instant when the ball is at its highest point.
