Astronomy 2
The following diagrams show five pairs of asteroids, labeled with their relative masses (M) and distances (d) between them. For example, an asteroid with M=2 has twice the mass of one with M=1 and a distance of d=2 is twice as large as a distance of d=1. Rank each pair from left to right based on the strength of the gravitational force attracting the asteroids to each other, from strongest to weakest.
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Absolute zero is
0° Celsius. 0° Fahrenheit. 0 Kelvin. 32° Fahrenheit. 273° Celsius.
In which position(s) of the Moon do we experience the highest high tides?
1 and 3
In which position(s) of the Moon do we experience the lowest low tides?
1 and 3
An atom of the element iron has an atomic number of 26 and an atomic weight of 56. If it is neutral, how many protons, neutrons, and electrons does it have?
13 protons, 43 neutrons, 13 electrons 26 protons, 56 neutrons, 26 electrons 26 protons, 30 neutrons, 26 electrons 26 protons, 30 neutrons, 30 electrons 13 protons, 56 neutrons, 13 electrons
What is the correct composition of a neutral atom of helium-4?
2 protons, 2 neutrons, 2 electrons
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?
20 m/s 10 m/s2 30 m/s2 30 m/s 10 m/s
The diagram shows a planet at four positions in its orbit. At which position does it have the greatest gravitational potential energy?
3
Of the temperature ranges below, which range represents the smallest range of actual temperature?
50-100° Fahrenheit 50-100° Celsius 50-100° Kelvin They all represent the same change in temperature.
If your mass is 60 kg on Earth, what would your mass be on the Moon?
60 kg 10 lb 60 lb 10 kg 50 kg
If two objects are the same size but one object is 3 times hotter than the other object, the hotter object emits
81 times more energy. 12 times more energy. 3 times more energy. 9 times more energy. none of the above
Choose the correct description of an object that is accelerating?
A car going around a circular track at a steady 100 miles per hour. A car traveling on a straight, flat road at 50 miles per hour. A car traveling on a straight uphill road at 30 miles per hour.
Which of the following statements about thermal radiation is always true?
A hot object emits more total radiation per unit surface area than a cool object. A hot object emits photons with a higher average energy than a cool object. A hot object emits more total radiation than a cool object. A hot object emits more X rays than a cool object. A hot object emits more radio waves than a cool object. A hot object emits less total radiation than a cool object.
Which of the following represents a change from potential energy to kinetic energy?
A kicked ball rising higher in the air and momentarily coming to rest at the top of its trajectory. A car applying its brakes on a straight road and heating up the brake pads as it slows. Sunlight melting a tray of ice. A rock starting from rest on a high cliff, then moving faster and faster as it falls.
Kepler: ________
A planet moves faster in the part of its orbit nearer the Sun and slower when farther from the Sun, sweeping out equal areas in equal times.
Which of the following statements about electrical charge is true?
A positive charge and a negative charge will repel each other. Two positive charges will attract each other. Two negative charges will attract each other. A positive charge and a negative charge will attract each other.
Which of the following statements correctly state general principles of motion? (Assume that the moving object's mass is not changing.) Select all that apply .
Accelerated motion includes any motion involving a change in speed, change in direction, or both. An object that is accelerating is also being acted upon by a (nonzero) net force. Motion in a circle at constant speed means zero acceleration. An object that is accelerating is also undergoing a change in momentum. A momentum change can occur even when the net force is zero.
The following diagrams are the same as those from Part A. This time, rank the pairs from left to right based on the size of the acceleration the asteroid on the left would have due to the gravitational force exerted on it by the object on the right, from largest to smallest.
According to Newton's second law, the asteroid with the largest acceleration will be the one that has the strongest gravitational force exerted on it by the object on the right. That is why the ranking here is the same as the ranking for Part A.
When an atom absorbs a photon containing energy, any of the following can happen except which? .
An electron moves from an upper energy level to a lower one. The atom is ionized. An electron moves from a lower energy level to an upper one. The atom becomes excited
Newton: _______
An object moves at constant velocity if there is no net force acting upon it.
Each diagram below shows a pair of spectra with a set of spectral lines. The top spectrum always shows the lines as they appear in a spectrum created in a laboratory on Earth ("Lab") and the bottom spectrum shows the same set of lines from a distant star. The left (blue/violet) end of each spectrum corresponds to shorter wavelengths and the right (red) end to longer wavelengths. Rank the five stars based on the Doppler shifts of their spectra, from largest blueshift, through no shift, to largest redshift.
As your answer correctly indicates, lines that are shifted to the left (toward the blue/violet) compared to the laboratory spectrum represent blue shifts, and lines shifted to the right (toward the red) represent redshifts.
The circles in the diagrams below represent energy levels in an atom, and the arrows show electron (blue dot) transitions from one energy level to another. (The spacing between circles represents differences in energy: A larger spacing means a greater difference in energy.) Assuming that the transitions occur as photons are emitted, rank the atoms based on the photon energy, from highest to lowest.
As your answer correctly shows, the emitted photon must have exactly the same amount of energy that the electron loses in moving from the higher to the lower energy level. Therefore the ranking of the photon energies must be in the same order as the amounts of energy lost by the electrons, and longer arrows mean greater changes in energy.
The diagrams below each show the motion of a distant star relative to Earth (not to scale). The red arrows indicate the speed and direction of the star's motion: Longer arrows mean faster speed. Rank the stars based on the Doppler shift that we would detect on Earth, from largest blueshift, through no shift, to largest redshift.
As your correct answer indicates, the star moving fastest toward Earth will have the greatest blueshift, the star moving across our line of sight will have no shift at all, and the star moving fastest away from us will have the greatest redshift.
Each of the following describes an "Atom 1" and an "Atom 2." In which case are the two atoms isotopes of each other?
Atom 1: nucleus with 92 protons and 143 neutrons, surrounded by 92 electrons Atom 2: nucleus with 92 protons and 146 neutrons, surrounded by 92 electrons
If you actually performed and compared the two trials chosen in Part C, you would find that, while the basketball and marble would hit the ground at almost the same time, it would not quite be exact: The basketball would take slightly longer to fall to the ground than the marble. Why?
Because gravity has a greater effect on the smaller ball. Because air resistance has a greater effect on the larger ball. Because gravity has a greater effect on the larger ball. Because air resistance has a greater effect on the smaller ball.
The following five diagrams show pairs of astronomical objects that are all separated by the same distance d. Assume the asteroids are all identical and relatively small, just a few kilometers across. Considering only the two objects shown in each pair, rank the strength, from strongest to weakest, of the gravitational force acting on the asteroid on the left.
Because the distance is the same for all five cases, the gravitational force depends only on the product of the masses. And because the same asteroid is on the left in all five cases, the relative strength of gravitational force depends on the mass of the object on the right. Continue to Part B to explore what happens if we instead ask about the gravitational force acting on the object on the right.
Which of the paths shown represent unbound orbits?
Both 2 and 3
As shown in the video, Earth has two tidal bulges at all times. Approximately where are these bulges located?
Both are on lines perpendicular to the Earth-Moon line. One faces the Moon and one faces opposite the Moon. One faces the Moon and one faces the Sun. One is over the Atlantic Ocean, and one is over the Pacific Ocean.
Assume you have completed the two trials chosen in Part A. Which of the following possible outcomes from the trials would support Newton's theory of gravity? Neglect effects of air resistance.
Both balls fall to the ground in the same amount of time. The more massive ball takes longer to reach the ground. The less massive ball takes longer to reach the ground. The two balls take different amounts of time to reach the ground.
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?
Both the total amount of energy and the rotation rate would remain the same. A tremendous amount of gravitational potential energy would be converted into other forms of energy, and the Sun would spin much more slowly. A tremendous amount of gravitational potential energy would be converted into other forms of energy, and the Sun would spin much more rapidly. The Sun would gain more energy and more angular momentum.
Suppose you lived on the Moon. Which of the following would be true?
Both your weight and your mass would be the same as they are on Earth. Your weight would be less than your weight on Earth, but your mass would be the same as it is on Earth. Your mass would be less than your mass on Earth, but your weight would be the same as it is on Earth. Both your weight and your mass would be less than they are on Earth.
Which of the following procedures would allow you to make a spectrum of the Sun similar to the one shown, though with less detail?
Compare the relative amounts of light that the Sun emits as infrared, visible light, and ultraviolet light. Take a photograph of the Sun and then use image-processing software to change the Sun's shape into a long, thin strip. Photograph the Sun through a powerful telescope. Pass a narrow beam of sunlight through a prism.
Consider the statement "There's no gravity in space." This statement is:
Completely false. False if you are close to a planet or moon, but true in between the planets. Completely true.
Suppose we want to know what the Sun is made of. What should we do?
Count the total number of black lines in the Sun's spectrum. Precisely measure the intensity of light in each of the black lines in the spectrum. Compare the wavelengths of lines in the Sun's spectrum to the wavelengths of lines produced by chemical elements in the laboratory. Find the precise wavelength at which the background rainbow of color peaks in brightness.
The _________ ______ allows us to determine how fast Mars is moving toward or away from us.
Doppler effect
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 __________.
Earth has a larger acceleration than the Moon, because it has a larger mass the Moon has a larger acceleration than Earth, because it has a smaller mass the Moon and Earth both have equal accelerations, because the forces are equal
According to the law of universal gravitation, what would happen to Earth if the Sun were somehow replaced by a black hole of the same mass?
Earth would be quickly sucked into the black hole. Earth would slowly spiral in to the black hole. Earth's orbit would not change.
Which of the following statements about electrons is not true?
Electrons have very little mass compared to protons or neutrons. Electrons can jump between energy levels in an atom only if they receive or give up an amount of energy equal to the difference in energy between the energy levels. An electron has a negative electrical charge. Within an atom, an electron can have only particular energies. Electrons orbit the nucleus rather like planets orbiting the Sun.
Electrons orbit an atomic nucleus like planets orbit the Sun.
True False
Suppose you are aboard a rocket that is orbiting Earth in the low, circular orbit shown. If you want to escape from Earth and head to the Moon or Mars along the "escape" path shown, what do you need to do?
Fire the rocket engine in your direction of travel, so that you gain speed. Turn the rocket around, and fire the engine so that you lose speed. The only way to end up on the "escape" path is to first return to Earth, then launch your rocket with escape velocity. Throw some excess supplies overboard, so that your rocket becomes less massive.
Newton: ________
For any force, there is an equal and opposite reaction force.
Newton: _______
Force = mass x acceleration
The diagrams below are the same as those from Part A. This time, rank the atoms based on the wavelength of the photon emitted as the electrons change energy levels, from longest to shortest.
From Part A, you already know the ranking of the photons by energy. Because higher energy means shorter wavelength, you have correctly found that the ranking for Part B is the reverse of that from Part A.
Why is Newton's version of Kepler's third law so useful to astronomers?
It allows us to calculate distances to distant objects. It tells us that more-distant planets orbit the Sun more slowly. It can be used to determine the masses of many distant objects. It explains why objects spin faster when they shrink in size.
Standing on the surface of the Earth you drop a rock down a well and it falls for 5 seconds before hitting the bottom. How fast is it moving when it hits the bottom of the well? Neglect air resistance.
It depends on how heavy it is. 15 m/s 10 m/s It depends on what shape it is. 50 m/s
Oxygen has atomic number 8. How many times must an oxygen atom be ionized to create an O+5 ion, and how many electrons will the ion have?
It doesn't have to be ionized; it just needs to gain five protons. It must be ionized five times; it now has three electrons. It must be ionized three times; it now has five electrons. It doesn't have to be ionized; it already has only three electrons. It must be ionized five times; it now has five electrons.
Where does the energy come from that your body uses to keep you alive?
It is created during the time that you rest or sleep. It is in the air that you breathe. It is produced from the radiative energy of the Sun on your skin. It comes from the foods you eat. It comes from the water you drink.
When a rock is held above the ground, we say it has some potential energy. When we let it go, it falls and we say the potential energy is converted to kinetic energy. Finally, the rock hits the ground. What has happened to the energy?
It is transformed back into gravitational potential energy.It is lost forever. Energy does not have to be conserved. The energy goes to producing sound and to heating the ground, rock, and surrounding air. The rock keeps the energy inside it (saving it for later use). The energy goes into the ground and, as a result, the orbit of the earth about the Sun is slightly changed.
How can an electron in an atom lose energy to go from a higher energy level to a lower energy level?
It loses gravitational potential energy. It releases a photon equal in energy to its own energy drop. It exchanges gravitational potential energy for kinetic energy. It absorbs a photon equal in energy to its own energy drop. It loses kinetic energy.
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. It will become much cooler. It will stay on its original orbit. It will also end up on an orbit that is closer to the Sun.
Imagine being on the Moon and looking at the thermal radiation spectrum of Earth. How would it compare to the spectra shown on the graph in the video?
It would be very similar to the spectrum of the human. It would be very similar to the spectrum of the Sun, except it would not rise so high on the graph. It would look like the spectrum of the human except it would rise much higher on the graph. It would be very similar to the spectrum of the 3000K star, except with less visible light.
What would happen if the Space Shuttle were launched with a speed greater than Earth's escape velocity?
It would travel away from Earth into the solar system. It would take less time to reach its bound orbit. It would travel in a higher orbit around Earth. It would be in an unstable orbit. It would orbit Earth at a faster velocity.
How are wavelength, frequency, and energy related for photons of light?
Longer wavelength means lower frequency and higher energy. Longer wavelength means lower frequency and lower energy. Longer wavelength means higher frequency and higher energy. There is no simple relationship because different photons travel at different speeds. Longer wavelength means higher frequency and lower energy.
As you watch the video, 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?
Low tides are highest at full moon and lowest at new moon. Low tides are highest at both full moon and new moon. High tides are highest at first- and third-quarter moon. Low tides are lowest at both full moon and new moon. High tides are highest at both full moon and new moon. High tides are highest at full moon and lowest at new moon.
Why does Mars appear reddish in color?
Mars's thermal radiation spectrum peaks in the infrared. It reflects most of the Sun's blue light while absorbing most of its red light. Mars is covered by rocks that emit mostly red light. It reflects most of the Sun's red light while absorbing most of its blue light.
Kepler: __________
More distant planets orbit the Sun at slower average speeds, obeying the precise mathematical relationship p2 =a3.
The fact that the Voyager spacecraft continues to travel out of the solar system, even though its rockets have no fuel, is an example of
Newton's second law of motion. the universal law of gravitation. Newton's third law of motion. Newton's first law of motion. none of the above.
The following diagrams are the same as those from Part A. Again considering only the two objects shown in each pair, this time rank the strength, from strongest to weakest, of the gravitational force acting on the object on the right.
Newton's third law tells us that the gravitational force exerted on the asteroid on the left by the object on the right will be equal in magnitude, but opposite in direction to the gravitational force exerted on the object on the right by the asteroid on the left. That is why the ranking here is the same as the ranking for Part A.
Rank the forms of light from left to right in order of increasing energy. To rank items as equivalent, overlap them.
Notice that the energy order is the same as the frequency order from Part B, which means it is opposite the wavelength order from Part A. The reason is that the energy of a photon of light is proportional to its frequency: energy = Planck's constant × frequency
Rank the forms of light from left to right in order of increasing frequency. To rank items as equivalent, overlap them.
Notice that the frequency order is the opposite of the wavelength order from Part A. You can understand why if you recall that wavelength times frequency always equals the speed of light. Because the speed of light is a constant, longer wavelengths must mean lower frequencies, and vice versa.
Which of the following correctly shows tidal bulges on Earth when the Moon is in the position shown?
Notice that there are two tidal bulges, one facing the Moon and one on the side of Earth opposite the Moon.
We divide the electromagnetic spectrum into six major categories of light, listed below. Rank these forms of light from left to right in order of increasing wavelength. To rank items as equivalent, overlap them.
Notice that these wavelengths span an enormous range. The wavelengths of gamma rays can be smaller than the size of an atomic nucleus, while the wavelengths of radio waves can be many meters (or even kilometers) long. Visible light spans only a very narrow range of wavelengths, from about 400 nanometers at the blue (violet) end to about 700 nanometers at the red end.
An important line of hydrogen occurs at a rest wavelength (as measured in a laboratory) of 656 nm (a nanometer (nm) is a billionth of a meter). Each diagram below has this line labeled with its wavelength in the spectrum of a distant star. Rank the motion of the stars along our line of sight (radial motion) based on their speed and direction, from moving fastest toward Earth, through zero (not moving toward or away from Earth), to moving fastest away from Earth.
Notice that your correct answer ranks the stars in wavelength order. The first two stars are moving toward us, because their lines have wavelength shorter than the rest wavelength of 656 nm. The last two stars are moving away from us, because their lines have wavelength longer than the rest wavelength of 656 nm.
Which of the following examples describes a situation where a car is experiencing a net force?
The car is making a gradual turn. The car is moving at constant speed. The car is floating on a stationary boat. The car is stopped on a hill.
Einstein's theory, like Newton's, predicts that, in the absence of air resistance, all objects should fall at the same rate regardless of their masses. Consider the following hypothetical experimental results. Which one would indicate a failure of Einstein's theory?
Scientists dropping balls on the Moon find that balls of different mass fall at slightly different rates. Scientists dropping balls from the Leaning Tower of Pisa find that balls of different size but the same mass fall at slightly different rates. Scientists dropping balls from the Leaning Tower of Pisa find that balls of different mass but the same size fall at slightly different rates.
We only see one face of the Moon from Earth because
The Moon is already tidally locked to the Earth. It is because the Moon does not rotate as it orbits. It just happened by chance.
Which of the following best describes why the Sun's spectrum contains black lines over an underlying rainbow?
The Sun produces a continuous rainbow of color, while the black lines are caused by atoms and molecules in Earth's atmosphere. The rainbow colors represent emission by particular chemical elements, while the black lines represent gaps where no element can emit light. The Sun's hot interior produces a continuous rainbow of color, but cooler gas at the surface absorbs light at particular wavelengths. The Sun produces a continuous rainbow of color, while the black lines are caused by imperfections in the instruments used to record the spectrum.
The diagram shows a planet at four positions in its orbit. At which position does it have the greatest angular momentum?
The angular momentum is the same at all four points.
Consider an atom of gold in which the nucleus contains 79 protons and 118 neutrons. What is its atomic number and atomic weight?
The atomic number is 79, and the atomic weight is 118. The atomic number is 118, and the atomic weight is 79. The atomic number is 79, and the atomic weight is 197. The atomic number is 118, and the atomic weight is 197.
Which person is weightless during the activity shown?
The diver is the only person that is in free-fall, and hence the only one that is weightless.
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. The elevator moves downward with constant velocity. The elevator moves upward while slowing in speed. The elevator moves upward with constant velocity. The elevator moves downward while increasing in speed.
Incandescent light bulbs emit thermal radiation because their filaments are heated to about 2500 Kelvin. LED light bulbs emit only at particular visible wavelengths. Why do incandescent bulbs require more energy to shine with the same amount of visible light as LED bulbs?
The filaments of incandescent light bulbs are much smaller than LED bulbs. Incandescent bulbs emit most of their energy as infrared light. Incandescent bulbs are larger than LED bulbs. Incandescent bulbs emit most of their energy as ultraviolet light.
Which of the following statements about the force attracting these two galaxies is true?
The force will get weaker as time passes. It is a force unlike any force that we ever experience on Earth. It is the same force that causes an apple to fall to the ground. It is a mysterious force, whose nature remains completely unknown to scientists.
You observe a distant galaxy. You find that a spectral line normally found in the visible part of the spectrum is shifted toward the infrared. What do you conclude?
The galaxy is moving away from you. The galaxy has very weak gravity. The galaxy is moving toward you. The galaxy is made purely of hydrogen. The composition of the galaxy is changing.
Consider an atom of gold in which the nucleus contains 79 protons and 118 neutrons. If it is doubly ionized, what is the charge of the gold ion and how many electrons remain in the ion?
The gold ion has a charge of +79 and no electrons. The gold ion has a charge of +2 and 79 electrons. The gold ion has a charge of +2 and 77 electrons. The gold ion has a charge of -2 and 77 electrons. The gold ion has a charge of +2 and 2 electrons.
Suppose a source at rest emits a spectrum that looks like the following:
The greater the redshift, the faster the speed away from you.
How does the Space Shuttle take off?
The hot rocket exhaust expands the air beneath the shuttle, propelling it forward. Its rocket engines push against the launch pad propelling the shuttle upwards. It converts mass-energy to kinetic energy. Hot gas shoots out from the rocket and, by conservation of momentum, the shuttle moves in the opposite direction. It achieves lift from its wings in the same way that airplanes do.
You observe the same spectral line in two stars that are identical in every way except that one rotates faster than the other. How does the spectral line differ between the two?
The line in the faster rotating star is redshifted. The line in the faster rotating star is broader. The line in the faster rotating star is narrower. The line in the faster rotating star is blueshifted. There is no difference.
If one object has a large redshift and another object has a small redshift, what can we conclude about these two objects?
The one with the large redshift is hotter and therefore is putting out more radiation. The one with the large redshift is moving away from us, and the one with the small redshift is moving toward us. The one with the large redshift is moving away from us faster than the one with the small redshift. The one with the large redshift is moving toward us faster than the one with the small redshift. The one with the large redshift is redder than the other one.
Kepler: ______
The orbit of each planet about the Sun is an ellipse with the Sun at one focus.
Suppose that Mars had a higher surface temperature. How would its spectrum be different?
The peak in the infrared would be at shorter wavelength. It would reflect more of the Sun's blue light. It would reflect more of the Sun's red light The peak in the infrared would be at longer wavelength.
Consider a planet orbiting another star that is very similar to our Sun. Assume the planet is about the size of Earth and has an Earth-like orbit around its star. Which of the following statements are true about the light coming from the star and planet?
The planet emits virtually all its light as infrared light. The planet emits more infrared light than the star. The star emits much more total light than the planet. The star's spectrum peaks in visible light.
Suppose you see two stars: a blue star and a red star. Which of the following can you conclude about the two stars? Assume that no Doppler shifts are involved. (Hint: Think about the laws of thermal radiation.)
The red star is more massive than the blue star. The red star has a hotter surface temperature than the blue star. The blue star has a hotter surface temperature than the red star. The blue star is farther away than the red star. The blue star is more massive than the red star.
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?
The second tidal bulge arises because gravity weakens with distance, essentially stretching Earth along the Earth-Moon line. The second tidal bulge is created by the Sun's gravity. The second tidal bulge is created by the centrifugal force caused by Earth's rapid rotation. 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.
Each diagram shows a single experimental trial in which you will drop a ball from some height. In each case, the ball's size, mass, and height are labeled. Note that two diagrams show a basketball, one diagram shows a bowling ball of the same size but larger mass, and one diagram shows a much smaller marble with the same mass as the basketball. You have a timer that allows you to measure how long it takes the ball to fall to the ground. Which pair of trials will allow you to test the prediction that an object's mass does not affect its rate of fall?
The simplest way to test the effects of mass is to compare the results of two trials that are identical except for the mass of the balls. In the language of experimental design, we say that the mass is the "variable of interest" for this experiment, and we therefore hold the other variables (size and height) constant so that they cannot affect the results.
Any spectrum can be displayed either in photographic form as shown to the left or as a graph. Which of the following graphs could represent a portion of the Sun's visible light spectrum?
The smooth part of the curve represents the graph of the background rainbow of color; the dips in the curve represent the black lines where light is missing from the rainbow.
Rank the forms of light from left to right in order of increasing speed. To rank items as equivalent, overlap them.
The speed of light is a constant (in empty space) for all forms of light, meaning that all forms of light travel at the same speed, regardless of wavelength, frequency, or energy.
From laboratory measurements, we know that a particular spectral line formed by hydrogen appears at a wavelength of 121.6 nanometers (nm). The spectrum of a particular star shows the same hydrogen line appearing at a wavelength of 121.8 nm. What can we conclude?
The star is getting colder. The "star" actually is a planet. The star is moving away from us. The star is getting hotter. The star is moving toward us.
From laboratory measurements, we know that a particular spectral line formed by hydrogen appears at a wavelength of 486.1 nanometers (nm). The spectrum of a particular star shows the same hydrogen line appearing at a wavelength of 485.9 nm. What can we conclude?
The star is moving toward us. The star is getting colder. The star is getting hotter. The "star" actually is a planet. The star is moving away from us.
If we observe one edge of a star to be redshifted and the opposite edge to be blueshifted, what can we conclude about the star?
The star is rotating. The star is in the process of formation. The star is actually two bodies, one moving toward us, the other away from us. The star's surface is very different from one side to the other. The star is in the process of falling apart.
We can learn a lot about the properties of a star by studying its spectrum. All of the following statements are true except one. Which one?
The total amount of light in the spectrum tells us the star's radius. The peak of the star's thermal emission tells us its temperature: Hotter stars peak at shorter (bluer) wavelengths. We can look at Doppler shifts of spectral lines to determine the star's speed toward or away from us. We can identify chemical elements present in the star by recognizing patterns of spectral lines that correspond to particular chemicals.
The diagram shows a planet at four positions in its orbit. At which position does it have the greatest total orbital energy? (Orbital energy is the sum of the planet's kinetic and gravitational potential energy.)
The total orbital energy is the same at all four positions.
Which of the following statements correctly describes the law of conservation of energy?
The total quantity of energy in the universe never changes. It is not really possible for an object to gain or lose potential energy, because energy cannot be destroyed. An object always has the same amount of energy. Energy can change between many different forms, such as potential, kinetic, and thermal, but it is ultimately destroyed. The fact that you can fuse hydrogen into helium to produce energy means that helium can be turned into hydrogen to produce energy.
Consider again the experimental trials from Part A. This time, you wish to test how the size of an object affects the rate of its fall. Which pair of trials should you compare?
The variable of interest is now size, so appropriate trials to compare are those in which size differs but other variables are constant.
In considering the Earth-Moon system we find
There are tidal forces on the Moon caused by the Earth there are tidal forces on the Earth and Moon caused by the Sun, but the Sun's tidal influence is less than the Earth's on the Moon or the Moon's on the Earth. There are tidal forces on the Earth caused by the Moon All of the above.
According to what we now know from Newton's laws, which of the following best explains why Kepler's second law is true?
This effect happens because of the influence of other planets on a particular planet's orbit. Orbits must be elliptical in shape. Gravity is an inverse cube law. A planet's angular momentum must be conserved as it moves around its orbit.
If an astronaut goes on a space walk outside the Space Station, she will quickly float away from the station unless she has a tether holding her to the station. Choose the correct explanation why does the statement make sense (or is clearly true) or does not make sense (or is clearly false).
This statement is false. She and the Space Station share the same orbit and will stay together unless they are pushed apart. This statement is false. She and the Space Station have different orbits at the beginning but will stay together due to mutual gravity. This statement is true. She and the Space Station cannot share the same orbit and will move apart quickly. This statement is true. She and the Space Station have different orbits at the beginning and will move apart.
When energy is converted from one form to another, a tiny amount is inevitably lost.
True False
X-rays always have more energy than radio waves.
True False
You are currently emitting electromagnetic waves.
True False
Which of the following best describes the origin of ocean tides on Earth?
Tides are caused on the side of Earth nearest the Moon because the Moon's gravity attracts the water. Tides are caused by the 23 1/2° tilt of the earth's rotational axis to the ecliptic plane. Tides are caused primarily by the gravitational force of the Sun. Tides are caused by the difference in the force of gravity exerted by the Moon across the sphere of the earth. The Moon's gravity pulls harder on water than on land, because water is less dense than rock.
Atomic nuclei consist of protons and electrons.
True False
Doubling the distance between two objects halves the gravitational force between them.
True False
If you are driving at 30 miles per hour and increase your speed to 60 miles per hour, you quadruple your kinetic energy.
True False
Process of Science: Gravity only affects very massive objects and we can therefore only test theories about it when looking at the orbits of planets.
True False
Speed and velocity are the same thing.
True False
The Moon is constantly falling toward Earth.
True False
The Moon is slowly moving away from Earth.
True False
The center of mass for Earth orbiting the Sun lies inside the Sun.
True False
The greater the wavelength of light, the greater its energy.
True False
The shorter the wavelength of light, the higher its frequency.
True False
There is no gravity in space.
True False
Lines of a particular element appear at the same wavelength in both emission and absorption line spectra.
True False
The atomic nuclei of the same element always have the same number of neutrons.
True False
The atomic nuclei of the same element always have the same number of protons.
True False
The energy levels for electrons vary from one element to another.
True False
Choose the correct description of what do we mean when we say that light is an electromagnetic wave and the relationship among wavelength, frequency, and speed for light waves.
We say that light is an electromagnetic wave because light is a oscillation of electric and magnetic fields.
Which of the following scenarios correctly demonstrates the transformation of mass into energy as given by Einstein's equation, E = mc2?
When hydrogen is fused into helium, whether in the Sun or in a nuclear bomb, the mass difference is turned into energy. An object accelerated to a great speed has a lot of kinetic energy. When you boil a pot of water, it has a high heat content, or thermal energy. A mass raised to a great height has a lot of gravitational potential energy. A burning piece of wood produces light and heat, therefore giving off radiative and thermal energy.
Which of the following statements about X rays and radio waves is not true?
X rays have higher frequency than radio waves. X rays have shorter wavelengths than radio waves. X rays have higher energy than radio waves. X rays and radio waves are both forms of light, or electromagnetic radiation. X rays travel through space faster than radio waves.
Which of the following statements about X rays and radio waves is not true?
X rays have shorter wavelengths than radio waves. Neither X rays nor radio waves can penetrate the earth's atmosphere. X rays and radio waves are both forms of light, or electromagnetic radiation. X rays have higher frequency than radio waves. X rays have higher energy than radio waves.
Most people are familiar with the rise and fall of ocean tides. Do tides also affect land?
Yes, land rises and falls with tides equally as high (and low) as the oceans. No, tides only affect the oceans. Yes, though land rises and falls by a much smaller amount than the oceans. No, tides can only affect liquids and gases, not solids.
Considering Einstein's famous equation, E = mc2, which of the following statements is true?
You can make mass into energy if you can accelerate the mass to the speed of light. One kilogram of mass represents 1 joule of energy. It takes a large amount of mass to produce a small amount of energy. Mass can be turned into energy, but energy cannot be turned back into mass. A small amount of mass can be turned into a large amount of energy.
Suppose you are in an elevator car when the elevator cable breaks. Which of the following correctly describes what happens and why.
You will crash your head into the elevator car ceiling because the car will be falling rapidly away from you. You float weightlessly within the elevator car because you and the elevator both begin to accelerate downward at the same rate. You float weightlessly within the elevator car because Earth's gravity is no longer tugging on you. You will crash your head into the elevator car ceiling because Earth's gravity will be pulling the car down faster than it pulls you down. You will remain stuck to the elevator floor as you and the elevator plunge downward toward a horrific crash.
Suppose you drive from home to your child's school, pick her up, and drive back home, covering a total distance of 25 miles in 1 hour. Which of the following statements are true?
Your average speed for the trip is zero. Your average speed for the trip is 25 miles per hour. You must accelerate when you reach the school. Your average velocity for the trip is 25 miles per hour. Your velocity is different on the return home than it is on the way to school.
Which object has the most kinetic energy?
a 4-ton truck moving 50 km/hr a 1-ton truck moving 110 km/hr a 3-ton truck moving 70 km/hr a 2-ton truck moving 90 km/hr A, B, C, and D all have the same kinetic energy.
Compared to the volume of its nucleus, the volume of an atom is about
a billion times greater. a million times greater. a thousand times greater. the same. a trillion times greater.
A perfectly opaque object that absorbs all radiation and reemits the absorbed energy as thermal radiation is
a cold, dense cloud of gas. a thermal emitter. an infrared radiation emitter. a hot, dense cloud of gas. transparent.
According to the laws of thermal radiation, hotter objects emit photons with _________.
a higher average speed a lower average energy a shorter average wavelength a lower average frequency
Kepler's second law of planetary motion:
a planet moves faster in the part of its orbit nearer the Sun and slower when farther from the Sun, sweeping out equal areas in equal times.
How much electrical charge does an atom with 6 protons, 6 neutrons, and 5 electrons have?
a total charge of +17 a positive charge of +7 a positive charge of +1 a negative charge of -5 none of the above
Carbon dioxide in Mars's atmosphere produces _______ _____ in the infrared portion of its spectrum.
absorption lines
On Earth, the _________ __ ________ tells us that the _______ of a falling object increases by about 10 m/s for each second it falls.
acceleration of gravity velocity
Which of the following type of spectrum would you expect if you view star light that has passed through a cool cloud of interstellar gas on its way to Earth?
an absorption line spectrum a continuous spectrum an emission line spectrum
Newton's first law of motion:
an object moves at constant velocity if there is no net force acting upon it.
The sum of the number of protons and neutrons in an atom is called the _________ ____ ________.
atomic mass number
Each chemical element has a unique _________ _________.
atomic number
The number of protons in an atom is called the atom's ________ ______.
atomic number
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?
because the gravitational force between Earth and the Moon is stronger than the gravitational force between Earth and the Sun because the Moon orbits Earth faster than Earth orbits the Sun because the gravitational attraction between Earth and the Moon varies more across Earth than does the gravitational attraction between Earth and the Sun
In the illustration of the solar spectrum, the upper left portion of the spectrum shows the __________ visible light.
brightest highest speed highest frequency lowest frequency lowest speed
When an electron in an atom goes from a higher energy state to a lower energy state, the atom
can absorb a photon of any frequency. emits a photon of a specific frequency. can emit a photon of any frequency. absorbs several photons of a specific frequency. absorbs a photon of a specific frequency.
An apple contains ___________ ________ energy that your body can convert into other forms energy.
chemical potential
A skater can spin faster by pulling her arms closer to her body or spin slower by spreading her arms out from her body. This is due to
conservation of angular momentum. the law of gravity. Newton's third law. conservation of energy. conservation of momentum.
Suppose an object is moving in a straight line at 50 miles/hr. According to Newton's first law of motion, the object will
continue to move in a straight line forever if it is in space, but slow and stop otherwise. continually slow down but never quite come to a complete stop. continue to move in the same way until it is acted upon by a force. eventually slow down and come to a stop. continue to move in the same way forever, no matter what happens.
According to the universal law of gravitation, if you triple the distance between two objects, then the gravitational force between them will
decrease by a factor of 9. decrease by a factor of 6. increase by a factor of 3. increase by a factor of 9. decrease by a factor of 3.
Suppose two objects are attracting each other gravitationally. If you double the distance between them, the strength of their gravitational attraction __________.
decreases by a factor of 4
If an object's velocity is doubled, its momentum is
dependent on its acceleration. halved. unchanged. quadrupled. doubled.
When an atom loses an electron, it becomes
dissociated. an isotope. vaporized. a plasma. ionized.
An atom with more electrons than protons has a negative _______ _______.
electric charge
The allowed shapes for orbits under the force of gravity are
ellipses and spirals. spirals, circles, and squares. ellipses, parabolas, and hyperbolas. ellipses only. ellipses, spirals, and parabolas.
Hot gas in Mars's upper atmosphere produces _______ _______ in the ultraviolet portion of its spectrum.
emission lines
Radiative energy is
energy of motion. energy from nuclear power plants. energy carried by light. energy used to power home radiators. heat energy.
For planets orbiting the Sun, period (p) and orbital distance (a) obey the relation p2 = a3
explains why Earth orbits the Sun at a faster average speed than Mars.
Kepler's third law of planetary motion
explains why Earth orbits the Sun at a faster average speed than Mars.
Kepler's first law of planetary motion
explains why Earth's distance from the Sun varies over the course of each year.
The orbit of each planet is an ellipse, with the Sun at one focus
explains why Earth's distance from the Sun varies over the course of each year.
A line between a planet and its Sun sweeps out equal areas in equal times
explains why Earth's orbital speed varies over the course of each year.
Kepler's second law of planetary motion
explains why Earth's orbital speed varies over the course of each year.
An object moves at constant velocity if there is no net force acting on it
explains why a spaceship with no forces acting on it will continue moving even if it has no fuel.
Newton's first law of motion
explains why a spaceship with no forces acting on it will continue moving even if it has no fuel.
Force equals mass times acceleration
explains why applying a force to a baseball with your arm can cause the baseball to accelerate from rest to the speed at which it leaves your hand.
Newton's second law of motion
explains why applying a force to a baseball with your arm can cause the baseball to accelerate from rest to the speed at which it leaves your hand.
Newton's third law of motion:
for any force, there is an equal and opposite reaction force.
Newton's second law of motion:
force = mass x acceleration
Momentum is defined as
force times velocity. mass times speed. mass times velocity. force times acceleration. mass times acceleration.
From shortest to longest wavelength, which of the following correctly orders the different categories of electromagnetic radiation?
gamma rays, X rays, ultraviolet, visible light, infrared, radio
The video shows a collapsing cloud of interstellar gas, which is held together by the mutual gravitational attraction of all the atoms and molecules that make up the cloud. As the cloud collapses, the overall force of gravity that draws the cloud inward _________________ because ______________________________.
gradually becomes stronger the strength of gravity follows an inverse square law with distance.
An asteroid that is moving farther from the Sun is gaining __________ _________ energy.
gravitational potential
The ultimate source of energy that powers the Sun is
gravitational potential energy of the contraction of the gas cloud that formed the Sun. mass energy of hydrogen fusing into helium. kinetic energy of the orbital motion of the Sun. chemical potential energy of hydrogen burning into helium. thermal energy of the hydrogen atoms in the Sun.
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.)
greater than your normal weight at rest equal to your normal weight at rest less than your normal weight at rest
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 equal to your normal weight at rest less than your normal weight at rest
The spectra of most galaxies show redshifts. This means that their spectral lines
have a higher intensity in the red part of the spectrum. have wavelengths that are shorter than normal. have normal wavelengths, but absorption of light makes them appear red. have wavelengths that are longer than normal. always are in the red part of the visible spectrum.
The spectra of most galaxies show redshifts. This means that their spectral lines _________.
have wavelengths that are shorter than normal always are in the red part of the visible spectrum have a higher intensity in the red part of the spectrum have wavelengths that are longer than normal
Compared to red light, blue light has higher frequency and
higher energy and shorter wavelength than red light. higher energy and longer wavelength than red light. lower energy and shorter wavelength than red light.
Which of the following are allowed orbital paths under gravity?
hyperbolic getting sucked in by gravity square parabolic elliptical
As the cloud shrinks in size, its central temperature ________ as a result of its ______________________________
increases gravitational potential energy being converted to thermal energy.
When white light passes through a cool cloud of gas, we see
infrared light. visible light. an emission line spectrum. thermal radiation. an absorption line spectrum.
Most hydrogen atoms have only a single proton in their nucleus, so a hydrogen atom that also has one neutron is an ______ of hydrogen.
isotope
Grass appears green because
it emits green light and absorbs other colors. it reflects green light and absorbs other colors. it transmits green light and emits other colors. it absorbs green light and emits other colors.
Thermal radiation gets its name because __________.
it is hot it makes objects warmer than they would be otherwise it is radiation that has a temperature its spectrum depends on the temperature of the object emitting it
The amount of gravitational potential energy released as an object falls depends on
its mass and its speed at the time it begins falling .its mass and the distance it falls, as well as the rate of gravitational acceleration. only its speed at the time it begins falling. only its mass. only the distance it falls.
Rapidly moving comets have more ______ energy than slowly moving ones.
kinetic
Gasoline is useful in cars because it has
kinetic energy. gravitational potential energy. electrical potential energy. radiative energy. chemical potential energy.
The mass of Jupiter can be calculated by
knowing the Sun's mass and measuring how Jupiter's speed changes during its elliptical orbit around the Sun. measuring the orbital period and distance of one of Jupiter's moons. measuring the orbital period and distance of Jupiter's orbit around the Sun. measuring the orbital speed of one of Jupiter's moons. knowing the Sun's mass and measuring the average distance of Jupiter from the Sun.
Red light has a _____ wavelength and a _____ frequency than does blue light.
longer, lower
Nuclear fusion in stars converts some of the _________ energy of hydrogen nuclei into light and heat.
mass
What quantities does angular momentum depend upon?
mass and velocity momentum and angular velocity force, velocity, and radius force and radius mass, velocity, and radius
Newton's second law of motion tells us that the net force applied to an object equals its
mass times energy. mass times acceleration. momentum times velocity. energy times acceleration. mass times velocity.
Compared to their values on Earth, on another planet your
mass would be the same but your weight would be different. weight would be the same but your mass would be different. mass and weight would both be the same.
Which of the following are forms of light (electromagnetic radiation)?
microwaves radio waves visible light infrared ultraviolet gamma rays X rays
Which of the following is not a conserved quantity?
momentum energy angular momentum radiation
An object's _________ is its mass times its velocity, and we say that it has ___________ _______ if it is rotating or turning on a curved path.
momentum angular momentum
Kepler's third law of planetary motion:
more distant planets orbit the Sun at slower average speeds, obeying the precise mathematical relationship p2 =a3.
If your momentum is changing, then a(n) ______ ______ must be acting on you.
net force
The loss of an electron from a neutral helium atom results in
neutral deuterium. ionized helium. ionized hydrogen. ionized deuterium. neutral hydrogen.
At which lunar phase(s) are tides least pronounced (e.g., the lowest high tides)?
new Moon both first and third quarters first quarter both new and full Moons full Moon
At which lunar phase(s) are tides most pronounced (e.g., the highest high tides)?
new Moon first quarter full Moon both new and full Moons both first and third quarters
According to the universal law of gravitation, the force due to gravity is
not dependent on the distance between objects. directly proportional to the distance between objects. directly proportional to the square of the distance between objects. inversely proportional to the square of the distance between objects. inversely proportional to the distance between objects.
Any particular location on Earth experiences __________.
one high tide and one low tide each day one high tide and one low tide each month two sets of high and low tides in the ocean, but only one set on land two high tides and two low tides each day two high tides and two low tides each month
The study of energy levels in atoms is called
quantum mechanics. special relativity. general relativity. particle physics. classical mechanics.
Thermal radiation is defined as
radiation that is felt as heat. radiation that depends only on the emitting object's temperature. radiation produced by a hot object. radiation in the form of emission lines from an object. radiation in the infrared part of the spectrum.
Thermal radiation is defined as _________.
radiation with a spectrum whose shape depends only on the temperature of the emitting object radiation in the form of emission lines from an object radiation produced by an extremely hot object radiation that is felt as heat
The light from Polaris travels through space in the form of _________ energy.
radiative
If you have a telescope that is observing light with wavelengths of a few meters, you are observing __________.
radio waves visible light infrared light ultraviolet light gamma rays X rays
If you heat a gas so that collisions are continually bumping electrons to higher energy levels, when the electrons fall back to lower energy levels the gas produces
radio waves. thermal radiation. an absorption line spectrum. an emission line spectrum. X rays.
From lowest energy to highest energy, which of the following correctly orders the different categories of electromagnetic radiation?
radio, infrared, visible light, ultraviolet, X rays, gamma rays
We can see each other in the classroom right now because we
reflect infrared light. emit thermal radiation. reflect visible light. emit visible light. emit infrared light.
Without telescopes or other aid, we can see the Moon because it
reflects infrared light. emits visible light. glows through radioactive decay. reflects visible light. emits thermal radiation.
Which of the following is an example in which you are traveling at constant speed but not at constant velocity?
rolling freely down a hill in a cart, traveling in a straight line driving backward at exactly 50 km/hr jumping up and down, with a period of exactly 60 hops per minute driving around in a circle at exactly 100 km/hr none of the above
X ray photons have a _____ wavelength, _____ frequency, and _____ energy than do ultraviolet photons.
shorter, higher, higher
Compared to a cold object, a hotter object of the same size emits most of its light at __________ wavelengths and emits _____ light overall.
shorter, less shorter, more longer, more the same, more
As the cloud shrinks in size, its rate of rotation ____________ because _______________________
speeds up its total angular momentum is conserved.
As a giant cloud of gas collapses due to gravity, you would expect its rate of rotation to
stay unchanged decrease increase
For any force, there is an equal and opposite reaction force
tells us that, when you are pushing on a table, the table is pushing up on you with a force that precisely balances the force of your push
Newton's third law of motion
tells us that, when your are standing, the ground is pushing up on you with a force that precisely balances the downward force of your weight.
Notice that the Sun's spectrum appears brightest (or most intense) in the yellow-green region. This fact tells us __________.
that the Sun's surface consists of a layer of cooler gas above a hotter interior that the Sun should appear yellow-green to our eyes the chemical composition of the Sun the approximate temperature of the Sun's surface
Tidal forces on Earth are causing
the Earth to orbit the Sun slower The Earth to speed up its rotation rate the Earth to slow down its rotation rate the Earth to orbit the Sun faster.
The wavelength of a wave is
the distance between where the wave is emitted and where it is absorbed. how strong the wave is. the distance between two adjacent peaks of the wave. equal to the speed of the wave times the wave's frequency. the distance between a peak of the wave and the next trough.
The frequency of a wave is
the number of peaks passing by any point each second. measured in cycles per second. measured in hertz (Hz). equal to the speed of the wave divided by the wavelength of the wave. all of the above
Kepler's first law of planetary motion:
the orbit of each planet about the Sun is an ellipse with the Sun at one focus.
The center of mass of a binary star system is
the point halfway in between them. the center of the least massive of the two stars. the center of the most massive of the two stars. the average mass of the two stars. the balance point of the system, around which the two objects would revolve.
In the formula E = mc2, what does E represent?
the radiative energy carried by light the electric charge of the object the gravitational potential energy of an object held above the ground the kinetic energy of a moving object the mass-energy, or potential energy stored in an object's mass
What does temperature measure?
the total potential energy of particles in a substance the average kinetic energy of particles in a substance the average size of particles in a substance the average mass of particles in a substance the total number of particles in a substance
Due to its much higher density, water heated to 80 degrees (Celsius) contains more _________ energy than air at the same temperature.
thermal
We determine Mars's surface temperature from the peak wavelength of the _________ ______ it emits.
thermal radiation
Why are astronauts (and other objects) weightless inside the International Space Station as it orbits Earth?
they are in free-fall the space station's engines fire to balance gravity there is no net force acting on the space station there's no gravity in space
If Earth were twice as far from the Sun, the force of gravity attracting Earth to the Sun would be:
twice as strong. half as strong one-quarter as strong.
As long as an object is not gaining or losing mass, a net force on the object will cause a change in
velocity. speed. acceleration. weight. direction.
Which forms of light are lower in energy and frequency than the light that our eyes can see?
visible light infrared and radio infrared and ultraviolet ultraviolet and X ray
The color of Mars in our sky is determined by the ________ ______ of Mars's spectrum.
visible portion
If you are in free-fall, then your _______ will be zero.
weight
If you stand on a scale on the Moon, your ______ will be different than it is on Earth but your _______ will be the same.
weight mass
In which of the following cases would you feel weightless?
while falling from an airplane with your parachute open while walking on the Moon while traveling through space in an accelerating rocket while falling from a roof none of the above
Which of the following objects is not a close approximation of a thermal emitter?
you a star hot, thin gas a filament in a light bulb a planet
Suppose that you had "X-ray vision" that allowed you to see X rays. What would you notice when you looked at a friend standing near you that you could not notice with your visible light vision alone?
you could see your friend's internal muscles but not bones nothing you could see your friend's internal bone structure
When you are standing on a scale in an elevator, what exactly does the scale measure?
your mass the force you exert on the scale the gravitational force exerted on you by Earth
