Describe retrograde motion
What will be an ideal response?
Planetary motion was a big problem for ancient astronomers. In fact, the word planet comes from the Greek word for "wanderer," referring to the eastward motion of the planets against the background of the fixed stars. The planets did not, however, move at a constant rate, and they could occasionally stop and move westward for a few months before resuming their eastward motion. This backward motion is called retrograde motion.
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Asteroid impacts large enough to cause mass extinction on Earth occur roughly once every 100 million years. Use that fact to estimate the probability that such an event will occur in your lifetime, which you can take to be approximately 100 years. What's your estimate of that probability?
A) 1 in 100,000,000 B) 1 in 10,000 C) 1 in 1,000,000 D) 1 in 100,000,000,000
An 80.0-kg object is falling and experiences a drag force due to air resistance. The magnitude of this drag force depends on its speed, v, and obeys the equation What is the terminal speed of this object?
A) 6.45 m/s B) 72.2 m/s C) 34.2 m/s D) 12.6 m/s E) 47.3 m/s
Interactions among galaxies also are thought to influence a galaxy's type in at least some cases. Which of the following does not support the idea that interactions can shape galaxies?
A) the presence of features, such as "tails" extending out of galaxies, bridges between galaxies, and rings of stars around galaxies B) the fact that galaxies with distorted appearances are more common at great distances than nearby C) computer modeling of collisions between galaxies D) the fact that more distant galaxies have larger redshifts
You stand three feet away from a plane mirror. How far is it from you to your image?
a. 4.0 ft c. 2.0 ft b. 6.0 ft d. 3.0 ft