Mastering Astronomy ch. 3
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?
- mass = 0.5 kg, size = marble, height = 30 m - mass 0.5 kg, size = basketball, height = 30 m
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?
- mass = 5.0 kg, size = bowling ball, height = 20 m - mass = 0.5 kg, size = basketball, height = 20 m
A vocabulary in context exercise in which students match words to definitions describing elliptical planetary orbits, applying ideas from Kepler's Laws of Planetary Motion.
1. Earth is located at one FOCUS of the Moon's orbit. 2. According to Kepler's second law, Jupiter will be traveling most slowly around the Sun when at APHELION 3. Earth orbits in the shape of a/an ELLIPSE around the Sun. 4. The mathematical form of Kepler's third law measures the period in years and the SEMIMAJOR AXIS in astronomical units (AU). 5. According to Kepler's second law, Pluto will be traveling fastest around the Sun when at PERIHELION. 6. The extent to which Mars' orbit differs from a perfect circle is called its ECCENTRICITY.
Which of the following is not true about a scientific theory?
A theory is essentially an educated guess.
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 air resistance has a greater effect on the larger ball.
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.
Consider again the set of observations from Part A. This time, classify each observation according to whether it is consistent with only the Earth-centered model, only the Sun-centered model, both models, or neither model. (Note that an observation is "consistent" with a model if that model offers a simple explanation for the observation.)
EARTH-CENTERED ONLY - a planet beyond Saturn rises in west, sets in east SUN-CENTERED ONLY - positions of nearby stars shift slightly back and forth each year - Mercury goes through a full cycle of phases BOTH MODELS - stars circle daily around north or south celestial pole - Moon rises in east, sets in west - a distant galaxy rises in east, sets in west each day NEITHER MODEL - we sometimes see a crescent Jupiter
Earth is closer to the Sun in January than in July. Therefore, in accord with Kepler's second law:
Earth travels faster in its orbit around the Sun in January than in July.
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 murder was orchestrated by an undetectable shadow government of the United States. - If he'd lived, Kennedy would have ended the Vietnam War. - The murder of John F. Kennedy was an act of evil. - Kennedy's death was the will of God.
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 observable universe contains approximately 100 billion galaxies. - Earth is at the center of the solar system. - The Sun is at the center of the solar system. - The chemical content of the universe is mostly hydrogen and helium. NOT FALSIFIABLE (COULD NOT BE PROVEN FALSE) - The universe was created by God. - The laws of nature are magnificent and beautiful. - We are all playthings in a computer program created by advanced aliens.
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.
FASTEST - Sun points to left - Sun points to bottom - Sun points to top right - Sun points to right SLOWEST
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.
FASTEST - asteroid on bottom - asteroid on bottom right - asteroid on top left - asteroid on top SLOWEST
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.)
FASTEST - smallest circle, planet on right - smallest oval, planet on right - medium circle, planet on bottom left - largest oval, planet on top left - largest circle, planet on top left SLOWEST
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.
LARGEST all are equal, in center box SMALLEST
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.)
LONGEST - 2AU: One Earth Mass & 2AU: Three Earth Mass (EQUAL, IN FIRST BOX) - 1AU: One Earth Mass & 1AU: Two Earth Mass (EQUAL, IN SECOND BOX) SHORTEST
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.
LONGEST - Sun points to left - Sun points to bottom - Sun points to top right - Sun points to right SHORTEST
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.
LONGEST - asteroid on bottom - asteroid on bottom right - asteroid on top left - asteroid on top SHORTEST
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.)
LONGEST - largest circle, planet on top left - largest oval, planet on top left - medium circle, planet on bottom left - smallest oval, planet on right - smallest circle, planet on right SHORTEST
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.)
LONGEST - largest circle, planet on top left - largest oval, planet on top left - medium circle, planet on bottom left - smallest oval, planet on right - smallest circle, planet on right SHORTEST
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.
LONGEST all are equal, in center box SHORTEST
Which of the following claims can be tested by scientific means?
People born when the Sun appears in the constellation Leo have larger average incomes than other people.
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) - positions of nearby stars shift slightly back and forth each year - stars circle daily around north of south celestial pole - Mercury goes through a full cycle of phases - a distant galaxy rises in east, sets in west each day - Moon rises in east, sets in west NOT REAL (FALSE STATEMENTS) - we sometimes see a crescent Jupiter - a planet beyond Saturn rises in west, sets in east
Listed following are distinguishing characteristics and examples of reflecting and refracting telescopes. Match these to the appropriate category.
REFLECTING TELESCOPES - The Hubble Space Telescope - Most commonly used by professional astronomers today - world's largest telescope REFRACTING TELESCOPES - very large telescopes become "top-heavy" - Galileo's telescopes - The world's largest is 1-meter in diameter - incoming light passes through glass
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.
Which of the following statements about an ellipse is not true?
The focus of an ellipse is always located precisely at the center of the ellipse.
Which of the following statements is not one of Newton's laws of motion?
What goes up must come down.
What was the Ptolemaic model?
an Earth-centered model of planetary motion published by Ptolemy
Tycho Brahe's contribution to astronomy included:
collecting data that enabled Kepler to discover the laws of planetary motion.
According to the universal law of gravitation, if you triple the distance between two objects, then the gravitational force between them __________.
decreases by a factor of 9
When Einstein's theory of gravity (general relativity) gained acceptance, it demonstrated that Newton's theory had been
incomplete.
We never see a crescent Jupiter from Earth because Jupiter __________.
is farther than Earth from the Sun
Scientific models are used to __________.
make specific predictions that can be tested through observations or experiments
Galileo's contribution to astronomy included:
making observations and conducting experiments that dispelled scientific objections to the Sun-centered model.
If Earth were twice as far as it actually is from the Sun, the force of gravity attracting Earth to the Sun would be
one-quarter as strong.
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
In science, a broad idea that has been repeatedly verified so as to give scientists great confidence that it represents reality is called a __________.
theory
