CH. 3-4
4b) 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? -Venus orbits the Sun faster than Earth orbits the Sun. -Pluto moves faster when it is closer to the Sun than when it is farther from the Sun. -Inner planets orbit the Sun at higher speed than outer planets. -Earth is slightly closer to the Sun on one side of its orbit than on the other side. -All the planets orbit the Sun in nearly the same plane. -The Sun is located slightly off-center from the middle of each planet's orbit.
-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. -None of the planets has a perfectly circular orbit, which means that all planets (including Earth) are closer to the Sun on one side of their orbit than on the other. The Sun's off-center position arises because it is located at a focus of each planet's elliptical orbit, rather than at the center of the ellipse.
4c) 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. -The Sun is located slightly off-center from the middle of each planet's orbit. -Venus orbits the Sun faster than Earth orbits the Sun. -Inner planets orbit the Sun at higher speed than outer planets. -All the planets orbit the Sun in nearly the same plane. -Earth is slightly closer to the Sun on one side of its orbit than on the other side.
-Pluto moves faster when it is closer to the Sun than when it is farther from the Sun. -The same ideas holds for any object orbiting the Sun: An object must move faster when it is closer to the Sun and slower when it is farther from the Sun.
2d) 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.
All the same -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.
2b) 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.
Picture answer -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.
4a) The video states that the planetary orbits are shown to scale. 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. -On the scale used to show the orbits in the video, all the planets would be microscopic in size.
11b) 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. -No, tides can only affect liquids and gases, not solids. -Yes, though land rises and falls by a much smaller amount than the oceans.
Yes, though land rises and falls by a much smaller amount than the oceans. Tides affect the entire Earth, but they are much more noticeable for the oceans because water flows so much more easily than land. Still, the land rises and falls about 1 centimeter with the tides.
6a) 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).
[Real:true statements] - Mercury goes through a full cycle of phases - Moon 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 - a distance galaxy rises in east, sets in west each day [Not real:false statements] - we sometimes see a crescent Jupiter - a planet beyond Saturn rises in west, sets in east
2a) 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.
all the same -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.
11c) Any particular location on Earth experiences __________. -two high tides and two low tides each day -two high tides and two low tides each month -two sets of high and low tides in the ocean, but only one set on land -one high tide and one low tide each day -one high tide and one low tide each month Submit
two high tides and two low tides each day -The video shows that any location on Earth passes through both tidal bulges and both tidal minima (the places where the tides are smallest) each day, which means two high tides and two low tides. Again, recall that this is true for both land and oceans, though tides are more noticeable in the oceans because water flows so much more readily than land.
12b) As the cloud shrinks in size, its rate of rotation __________ because __________. - slows down - speeds up - stays constant at all times - the force of gravity strengthens as the cloud shrinks - its total energy is conserved - its total angular momentum is conserved
(Blank 1) speeds up (Blank 2) 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.)
12d) 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 slowly. -A tremendous amount of gravitational potential energy would be converted into other forms of energy, and the Sun would spin much more rapidly. -Both the total amount of energy and the rotation rate would remain the same. -The Sun would gain more energy and more angular momentum.
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.)
12e) 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 stay on its original orbit. -It will end up on an orbit that is farther from the Sun. -It will also end up on an orbit that is closer to the Sun. -It will become much cooler.
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.)
12c) As the cloud shrinks in size, its central temperature __________ as a result of its __________. - stays constant - decreases - increases - gravitational potential energy being converted to thermal energy - kinetic energy being converted to radiative energy - thermal energy being converted to radiative energy
(Blank 1) increases (Blank 2) 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.)
9a) The following five diagrams show pairs of astronomical objects that are all separated by the same distance dd
- asteroid:sun - asteroid:earth - asteroid:moon - asteroid:asteroid - asteroid:hydrogen atom -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.
6c)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 -planets beyond Saturn must orbit the Sun more slowly than closer-in planets -there are no planets beyond Saturn -all objects in space must orbit the Sun in the same direction
- the rise and set of all objects depend only on Earth's rotation -Earth rotates from west to east, so objects in the sky must appear to go across our sky from east to west.
11e) 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? -High tides are highest at first- and third-quarter moon. -High tides are highest at full moon and lowest at new moon. -Low tides are lowest at both full moon and new moon. -Low tides are highest at full moon and lowest at new moon. -High tides are highest at both full moon and new moon. -Low tides are highest at both full moon and new moon.
-Low tides are lowest at both full moon and new moon. -High tides are highest at both full moon and new moon. -As the video shows, the tidal bulges are largest and the tidal minima are smallest at full moon and new moon. Those are the times when the tidal forces of the Sun and Moon align (and therefore add to one another). Therefore, high tides are higher and low tides are lower at these times, which are called spring tides. (In contrast, we have neap tides at first- and third-quarter moons, when high tides are not as high and low tides are not as low.)
6d) We never see a crescent Jupiter from Earth because Jupiter __________. -shines with its own light -does not go around Earth -orbits the Sun in the same direction as Earth -is farther than Earth from the Sun
-is farther than Earth from the Sun -An object must come between Earth and the Sun for us to see it in a crescent phase, which is why we see crescents only for Mercury, Venus, and the Moon.
9d) 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 -Earth has a larger acceleration than the Moon, because it has a larger mass -the Moon and Earth both have equal accelerations, because the forces are equal
-the Moon has a larger acceleration than Earth, because it has a smaller mass -Newton's second law of motion, F=ma, means that for a particular force F, the product mass x acceleration must always be the same. Therefore if mass is larger, acceleration must be smaller, and vice versa.
8) 1. The light from Polaris travels through space in the form of _____ energy. 2. Rapidly moving comets have more_____ energy than slowly moving ones. 3. An apple contains _____ energy that your body can convert into other forms energy. 4. Nuclear fusion in stars converts some of the _____ energy of hydrogen nuclei into light and heat. 5. Due to its much higher density, water heated to 80 degrees (Celsius) contains more_____ energy than air at the same temperature. 6. An asteroid that is moving farther from the Sun is gaining _____energy. -Chemical potential -radiative -kinetic -mass- -thermal -Gravitational potential
1) radiative 2) kinetic 3) chemical potential 4) mass- 5) thermal 6) gravitational potential
3a) The following diagrams all show the same star, but each shows a different planet orbiting the star. The diagrams are all scaled the same. (For example, you can think of the tick marks along the line that passes through the Sun and connects the nearest and farthest points in the orbit as representing distance in astronomical units (AU).) Rank the planets from left to right based on their average orbital distance from the star, from longest to shortest. (Distances are to scale, but planet and star sizes are not.)
Biggest to smallest -Note that the line that passes through the star and connects the nearest and farthest points of the planet's orbit is called the major axis, and half this line is the semimajor axis— which we consider the planet's average distance from the star.
11a) 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 is over the Atlantic Ocean, and one is over the Pacific Ocean. -One faces the Moon and one faces the Sun.
One faces the Moon and one faces opposite the Moon. -The tidal bulges face toward and away from the Moon, because they are caused primarily by the gravitational attraction between Earth and the Moon. Friction explains why the bulges are slightly ahead of the Earth-Moon line, rather than directly on the Earth-Moon line. We'll ignore that detail for now.
2f) 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.
Picture answer -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.
1a) 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 -A full Venus always occurs when it is on the opposite side of the Sun as viewed from Earth. Galileo used this fact as evidence for the Sun-centered view of the solar system: The fact that Venus goes through all the phases must mean it goes all the way around the Sun. In contrast, in the Ptolemaic model, Venus only varies between new and crescent phases.
9c) 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.
- asteroid:sun - asteroid:earth - asteroid:moon - asteroid:asteroid - asteroid:hydrogen atom -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.
9b) 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.
- asteroid:sun - asteroid:earth - asteroid:moon - asteroid:asteroid - asteroid:hydrogen atom -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.
1e) 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. -In the Ptolemaic system, we should never see more than a crescent for Venus. Because we do in fact see more, the Ptolemaic model must be wrong. The full range of phases that we see for Venus is consistent only with the idea that Venus orbits the Sun. Galileo was the first to observe the phases of Venus — and hence to find this evidence in support of the Sun-centered system — because he was the first to observe Venus through a telescope. Without a telescope, we cannot tell that Venus goes through phases.
10c) 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.
-d=1, m=2, m=2 -d=1, m=1, m=2 -d=1, m=1, m=1 -d=2, m=1, m=2 -d=2, m=1, m=1 -
5) 1. Earth is located at one _____of the Moon's orbit. 2. According to Kepler's second law, Jupiter will be traveling most slowly around the Sun when at_____. 3. Earth orbits in the shape of a/an_____ around the Sun. 4. The mathematical form of Kepler's third law measures the period in years and the_____ in astronomical units (AU). 5. According to Kepler's second law, Pluto will be traveling fastest around the Sun when at_____ . 6. The extent to which Mars' orbit differs from a perfect circle is called its_____. -Perihelion -focus -semimajor axis -aphelion -eccentricity -ellipse
1) focus 2)aphelion 3)ellipse 4)semimajor axis 5)Perihelion 6)eccentricity
1c) When would a new Venus be highest in the sky?
at noon -A new Venus occurs when Venus is directly between the Sun and Earth, which means a new Venus will be highest in the sky at the same time that the Sun is highest in the sky, which is around noon (local time).
1b) 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 -Because Venus is full when it is on the opposite side of the Sun from Earth, the Sun and Venus both appear to move through the sky together at that time. Venus therefore rises with the Sun, reaches its highest point at noon, and sets with the Sun.
10b) The following diagrams are the same as those from Part A. This time, rank the five positions of the spaceship from left to right based on the strength of the gravitational force that the Moon exerts on the spaceship, from strongest to weakest.
picture answer Gravity follows an inverse square law with distance, which means the force of gravity between the Moon and the spaceship increases as the spaceship approaches the Moon. Now continue to Part C for activities that look at the effects of both distance and mass on gravity.
4d) 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 p ^2=a^3. Which of the following statements describe a characteristic of the solar system that is explained by Kepler's third law? -Pluto moves faster when it is closer to the Sun than when it is farther from the Sun. -All the planets orbit the Sun in nearly the same plane. -Venus orbits the Sun faster than Earth orbits the Sun. -The Sun is located slightly off-center from the middle of each planet's orbit. -Earth is slightly closer to the Sun on one side of its orbit than on the other side. -Inner planets orbit the Sun at higher speed than outer planets.
-Venus orbits the Sun faster than Earth orbits the Sun -Inner planets orbit the Sun at higher speed than outer planets -From the relationship p2=a3p2=a3, it follows that planets closer to the Sun must orbit at higher average speeds than planets farther from the Sun. For example, Venus must orbit the Sun faster than Earth because Venus is closer to the Sun.
3b) The following diagrams are the same as those from Part A. This time, rank the planets from left to right based on the amount of time it takes each to complete one orbit, 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. (Distances are to scale, but planet and star sizes are not.)
Biggest to smallest -Recall that the time it takes a planet to complete an orbit is called its orbital period. The pattern found in this Part illutrates one of the ideas that are part of Kepler's third law: Planets with larger average orbital distances have longer orbital periods.
2c) 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.
Picture answer -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.
2e) 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.
Picture answer -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.
11d) 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 is created by the Sun's gravity. -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 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
The second tidal bulge arises because gravity weakens with distance, essentially stretching Earth along the Earth-Moon line -Tides are created by gravity, and the tidal force is caused by the fact that gravity weakens with distance. Therefore, the parts of Earth that are closer to the Moon feel a stronger gravitational attraction to the Moon, and the parts of Earth that are farther away feel a weaker gravitational attraction to the Moon. This varying gravitational attraction essentially stretches Earth along the Earth-Moon line, creating tidal bulges on both sides.
1d) When would you expect to see Venus high in the sky at midnight?
Never -For Venus to be high in the sky at midnight, it would have to be on the opposite side of our sky from the Sun. But that never occurs because Venus is closer than Earth to the Sun.
12a) 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 draws the cloud inward __________ because __________. - gradually becomes stronger - gradually becomes weaker - stays constant at all times - the strength of gravity follows an inverse square law with distance - the mass of the cloud increases as it collapses - the total gravitational force is a conserved quantity
(Blank 1) gradually becomes stronger (Blank 2) 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. This 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.)
11f) 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 attraction between Earth and the Moon varies more across Earth than does the gravitational attraction between Earth and 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 -The Sun exerts a stronger gravitational force on Earth, which is why Earth orbits the Sun. However, tides are caused by the variation in the gravitational attraction across Earth. Even though the gravitational attraction between Earth and the Moon is smaller than the attraction between Earth and the Sun, the Moon's much closer distance makes this attraction vary more across Earth. That is why tides are due primarily to the Moon, with only a secondary effect from the Sun.
3d) Each of the following diagrams shows a planet orbiting a star. Each diagram is labeled with the planet's mass (in Earth masses) and its average orbital distance (in AU). Assume that all four stars are identical. Use Kepler's third law to rank the planets from left to right based on their orbital periods, 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. (Distances are to scale, but planet and star sizes are not.)
2 AU, both masses- Longest 1 AU, bot masses- Shortest -Kepler's third law tells us that the orbital period of the planet depends on its average distance from its star, but not on the planet's mass. As Newton later showed with his version of Kepler's third law, this is actually an approximation that works well whenever the planet's mass is small compared to the mass of the star.
3c) The following diagrams are the same as those from Parts A and B. This time, rank the planets from left to right based on their average orbital speed, 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. (Distances are to scale, but planet and star sizes are not.)
Smallest to biggest -This pattern illustrates another of the ideas that are part of Kepler's third law: Planets with larger average orbital distances have slower average speeds.
6b) 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] - Mercury goes through a full cycle of phases - positions of nearby stars shift slightly back and forth each year [Both models] - stars circle daily around north or south celestial pole - moon rises in east, sets in west each day - a distant galaxy rises in east, sets in west each day [Neither model] - we sometimes see a crescent Jupiter
7a) Let's start with an example from history. Listed below are a series of claims regarding United States President John F. Kennedy (1917-1963). Classify each statement according to whether or not it is falsifiable.
[Falsifiable:could be proven false] - Kennedy was the 35th president of the United States - Kennedy died from a bullet in his brain [Not falsifiable:could not be proven false] - Kennedy's death was the will of God - The murder of John F. Kennedy was an act of evil - If he'd lived, Kennedy would have ended the Vietnam War - Kennedy's murder was orchestrated by an undetectable shadow government of the United States -Note that both of the falsifiable claims in this example happen to be true. The claim about Kennedy being the 35th President is falsifiable because it can be checked against historical records. The claim that Kennedy died from a bullet in his brain is falsifiable because it could have been shown false by the medical examiner. The remaining claims are not falsifiable: Statements that call on any type of supernatural being are by definition out of the realm of science. Similarly, a claim of something being "undetectable" could not be falsified, and a claim about what Kennedy would have done if he had lived is a conjecture that cannot be disproven.
7b) Let's now consider possible scientific claims. Recall that a scientific claim is falsifiable if it could in principle be shown to be false by observations or experiments, even if those observations or experiments have not yet been performed. Classify each claim according to whether or not it is falsifiable.
[Falsifiable:could be proven false] - The chemical content of the universe is mostly hydrogen and helium - Earth is at the center of the solar system - The Sun is at the center of the solar system - The observable universe contains approximately 100 billion galaxies [Not falsifiable:could not be proven false] - We are all playthings in a computer program created by advanced aliens - The laws of nature are magnificent and beautiful - The universe was created by God -Note that falsifiability alone does not make something science. However, scientific models must make predictions that can be tested, and in general we can only test claims or predictions that are falsifiable.
10a) Each of the following diagrams shows a spaceship somewhere along the way between Earth and the Moon (not to scale); the midpoint of the distance is marked to make it easier to see how the locations compare. Rank the five positions of the spaceship from left to right based on the strength of the gravitational force that Earth exerts on the spaceship, from strongest to weakest. (Assume the spaceship has the same mass throughout the trip; that is, it is not burning any fuel.)
picture answer Gravity follows an inverse square law with distance, which means the force of gravity between Earth and the spaceship weakens as the spaceship gets farther from Earth.
