# Astronomy Test 2

 The movement of a pool ball, after being struck by a cue, is an example of Newton's second law of motion. When did Ptolemy live? about 2000 years ago What is meant by a hypothesis? an explanation for a phenomenon that makes a prediction When Copernicus first created his Sun-centered model of the universe, it did not lead to substantially better predictions of planetary positions than the Ptolemaic model. Why not? Copernicus used perfect circles for the orbits of the planets. How does the Space Shuttle take off? Hot gas shoots out from the rocket and, by conservation of momentum, the shuttle moves in the opposite direction. Which of the following was not observed by Galileo? stellar parallax What is meant by Occam's Razor? the idea that scientists should prefer the simpler of two models that agree equally well with observations As long as an object is not gaining or losing mass, a net force on the object will cause a change in velocity Historians trace the origins of a 24-hour day to the ancient Egyptians. Ptolemy was important in the history of astronomy because he developed a model of the solar system that made sufficiently accurate predictions of planetary positions to remain in use for many centuries. If an object's velocity is doubled, its momentum is doubled. Which of the following is not one of, nor follows directly from, Kepler's laws? The force of attraction between any two objects decreases with the square of the distance between their centers. How did the Ptolemaic model explain the apparent retrograde motion of the planets? It held that the planets moved along small circles that moved on larger circles around Earth. Suppose an object is moving in a straight line at 50 mi/hr. According to Newton's first law of motion, the object will continue to move in the same way until it is acted upon by a force. Kepler's second law, which states that as a planet moves around its orbit it sweeps out equal areas in equal times, means that a planet travels faster when it is nearer to the Sun and slower when it is farther from the Sun. He discovered that Jupiter has moons. Galileo In which of the following cases would you feel weightless? while falling from a roof During the Dark Ages in Europe, the scientific work of the ancient Greeks was preserved and further developed primarily by scholars in Baghdad Momentum is defined as mass times velocity. Which of the following is an example in which you are traveling at constant speed but not at constant velocity? driving around in a circle at exactly 100 km/hr He was the first to prove that comets lie beyond Earth's atmosphere. Tycho Brahe He discovered that the orbits of planets are ellipses. Kepler What is the acceleration of gravity of Earth? 9.8 m/s2 downward By the late 1600s, science and technology in China fell behind that of Europe. Many historians believe that this happened because a culture of secrecy discouraged broad collaborative efforts. How did Eratosthenes estimate the size of Earth in 240 B.C.? by comparing the maximum altitude of the Sun in two cities at different latitudes Changing the orbit of a spacecraft by firing thrusters is an example of Newton's third law of motion. Compared with the standard hour of 60 minutes used today, the hour of ancient Egypt was longer than 60 minutes in the summer and shorter than 60 minutes in the winter. If your mass is 60 kg on Earth, what would your mass be on the Moon? 60 kg Which of the following statements is not one of Newton's laws of motion? What goes up must come down. He discovered what we now call Newton's first law of motion. Galileo What quantities does angular momentum depend upon? mass, velocity, and radius You are standing on a scale in an elevator. Suddenly you notice your weight decreases. What do you conclude? The elevator is accelerating downwards. Newton's second law of motion tells us that the net force applied to an object equals its mass times acceleration. 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. 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. Which ancient culture had the greatest known success in predicting eclipses? Mayans The controversial book of this famous person, published in 1543 (the year of his death), suggested that Earth and other planets orbit the Sun. Copernicus Kepler's third law, p2 = a3, means that All of the above are correct. Which of the following statements about scientific models is true? A model can be used to explain and predict real phenomena. The fact that the Voyager spacecraft continue to speed out of the solar system, even though its rockets have no fuel, is an example of Newton's first law of motion. Authorvrk09a ID40731 Card SetAstronomy Test 2 DescriptionTest 2 Updated2010-10-08T21:49:58Z Show Answers