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04 Testbank
Astronomy (Sc/Nats 1740)
York University
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The Cosmic Perspective, 7e (Bennett et al.) Chapter 4 Making Sense of the Universe: Understanding Motion, Energy, and Gravity 4 Multiple-Choice Questions 1) Which of the following is an example in which you are traveling at constant speed but not at constant velocity? A) rolling freely down a hill in a cart, traveling in a straight line B) driving backward at exactly 50 km/hr C) driving around in a circle at exactly 100 km/hr D) jumping up and down, with a period of exactly 60 hops per minute E) none of the above Answer: C 2) What is the acceleration of gravity of Earth? A) 9 m/s2 downward B) 9 m/s downward C) 9 km/s2 downward D) 9 m2/s downward E) 9 km/s downward Answer: A 3) If you drop a rock from a great height, about how fast will it be falling after 5 seconds, neglecting air resistance? A) It depends on how heavy it is. B) It depends on what shape it is. C) 10 m/s D) 15 m/s E) 50 m/s Answer: E 4) Momentum is defined as A) mass times speed. B) mass times velocity. C) force times velocity. D) mass times acceleration. E) force times acceleration. Answer: B 5) If an object's velocity is doubled, its momentum is A) halved. B) unchanged. C) doubled. D) quadrupled. E) dependent on its acceleration. Answer: C 1 Copyright By Jihao Zhou. 6) As long as an object is not gaining or losing mass, a net force on the object will cause a change in A) acceleration. B) direction. C) weight. D) speed. E) velocity. Answer: E 7) If your mass is 60 kg on Earth, what would your mass be on the Moon? A) 10 lb B) 10 kg C) 50 kg D) 60 kg E) 60 lb Answer: D 8) In which of the following cases would you feel weightless? A) while walking on the Moon B) while falling from an airplane with your parachute open C) while traveling through space in an accelerating rocket D) while falling from a roof E) none of the above Answer: D 9) You are standing on a scale in an elevator. Suddenly you notice your weight decreases. What do you conclude? A) The elevator is accelerating upwards. B) The elevator is moving at a constant velocity upwards. C) The elevator is accelerating downwards. D) The elevator is moving at a constant velocity downwards. E) Your diet is working. Answer: C 10) What would happen if the Space Shuttle were launched with a speed greater than Earth's escape velocity? A) It would travel away from Earth into the solar system. B) It would travel in a higher orbit around Earth. C) It would take less time to reach its bound orbit. D) It would orbit Earth at a faster velocity. E) It would be in an unstable orbit. Answer: A 2 Copyright By Jihao Zhou. 16) The fact that the Voyager航海者 spacecraft continue to speed out of the solar system, even though its rockets have no fuel, is an example of A) Newton's first law of motion. B) Newton's second law of motion. C) Newton's third law of motion. D) the universal law of gravitation. E) none of the above. Answer: A 17) Changing the orbit of a spacecraft by firing thrusters is an example of A) Newton's first law of motion. B) Newton's second law of motion. C) Newton's third law of motion. D) the universal law of gravitation. E) none of the above. Answer: C 18) What quantities does angular momentum depend upon? A) mass and velocity B) mass, velocity, and radius C) force and radius D) force, velocity, and radius E) momentum and angular velocity Answer: B 19) 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 A) the law of gravity. B) Newton's third law. C) conservation of momentum. D) conservation of angular momentum. E) conservation of energy. Answer: D 20) Which of the following is not a conserved quantity? A) energy B) momentum C) angular momentum D) radiation Answer: D 4 Copyright By Jihao Zhou. 21) Which of the following is not a unit of energy? A) Calorie B) joule C) calorie D) kilowatt E) British thermal unit Answer: D 22) Radiative energy is A) heat energy. B) energy from nuclear power plants. C) energy carried by light. D) energy used to power home radiators. E) energy of motion. Answer: C 23) Gasoline is useful in cars because it has A) gravitational potential energy. B) chemical potential energy. C) electrical potential energy. D) kinetic energy. E) radiative energy. Answer: B 24) Which of the following is a form of electrical potential energy? A) coal B) energy coming to your house from power companies C) energy from the Sun D) light from a fluorescent bulb E) moving blades on an electric mixer Answer: B 25) Which object has the most kinetic energy? A) a 4-ton truck moving 50 km/hr B) a 3-ton truck moving 70 km/hr C) a 2-ton truck moving 90 km/hr D) a 1-ton truck moving 110 km/hr E) A, B, C, and D all have the same kinetic energy. Answer: C 26) Of the temperature ranges below, which range represents the smallest range of actual temperature? A) 50-100° Kelvin B) 50-100° Celsius C) 50-100° Fahrenheit D) They all represent the same change in temperature. Answer: C 5 Copyright By Jihao Zhou. 32) Considering Einstein's famous equation, E = mc2, which of the following statements is true? A) Mass can be turned into energy, but energy cannot be turned back into mass. B) It takes a large amount of mass to produce a small amount of energy. C) A small amount of mass can be turned into a large amount of energy. D) You can make mass into energy if you can accelerate the mass to the speed of light. E) One kilogram of mass represents 1 joule of energy. Answer: C 33) Which of the following scenarios correctly demonstrates the transformation of mass into energy as given by Einstein's equation, E = mc2? A) When hydrogen is fused into helium, whether in the Sun or in a nuclear bomb, the mass difference is turned into energy. B) An object accelerated to a great speed has a lot of kinetic energy. C) A mass raised to a great height has a lot of gravitational potential energy. D) When you boil a pot of water, it has a high heat content, or thermal energy. E) A burning piece of wood produces light and heat, therefore giving off radiative and thermal energy. Answer: A 34) The ultimate source of energy that powers the Sun is A) chemical potential energy of hydrogen burning into helium. B) mass energy of hydrogen fusing into helium. C) gravitational potential energy of the contraction of the gas cloud that formed the Sun. D) kinetic energy of the orbital motion of the Sun. E) thermal energy of the hydrogen atoms in the Sun. Answer: B 35) Which of the following statements correctly describes the law of conservation of energy? A) An object always has the same amount of energy. B) Energy can change between many different forms, such as potential, kinetic, and thermal, but it is ultimately destroyed. C) The total quantity of energy in the universe never changes. D) The fact that you can fuse hydrogen into helium to produce energy means that helium can be turned into hydrogen to produce energy. E) It is not really possible for an object to gain or lose potential energy, because energy cannot be destroyed. Answer: C 36) Where does the energy come from that your body uses to keep you alive? A) It is produced from the radiative energy of the Sun on your skin. B) It comes from the foods you eat. C) It comes from the water you drink. D) It is in the air that you breathe. E) It is created during the time that you rest or sleep. Answer: B 7 Copyright By Jihao Zhou. 37) 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? A) The energy goes into the ground and, as a result, the orbit of the earth about the Sun is slightly changed. B) The energy goes to producing sound and to heating the ground, rock, and surrounding air. C) The rock keeps the energy inside it (saving it for later use). D) It is lost forever. Energy does not have to be conserved. E) It is transformed back into gravitational potential energy. Answer: B 38) According to the universal law of gravitation, the force due to gravity is A) directly proportional to the square of the distance between objects. B) inversely proportional to the square of the distance between objects. C) directly proportional to the distance between objects. D) inversely proportional to the distance between objects. E) not dependent on the distance between objects. Answer: B 39) The force of gravity is an inverse square law. This means that, if you double the distance between two large masses, the gravitational force between them A) also doubles. B) strengthens by a factor of 4. C) weakens by a factor of 4. D) weakens by a factor of 2. E) is unaffected. Answer: C 40) According to the universal law of gravitation, if you triple the distance between two objects, then the gravitational force between them will A) increase by a factor of 3. B) decrease by a factor of 3. C) decrease by a factor of 6. D) increase by a factor of 9. E) decrease by a factor of 9. Answer: E 41) According to the universal law of gravitation, if you double the masses of both attracting objects, then the gravitational force between them will A) not change at all. B) increase by a factor of 2. C) decrease by a factor of 2. D) increase by a factor of 4. E) decrease by a factor of 4. Answer: D 8 Copyright By Jihao Zhou. 47) The mass of Jupiter can be calculated by A) measuring the orbital period and distance of Jupiter's orbit around the Sun. B) measuring the orbital period and distance of one of Jupiter's moons. C) measuring the orbital speed of one of Jupiter's moons. D) knowing the Sun's mass and measuring how Jupiter's speed changes during its elliptical orbit around the Sun. E) knowing the Sun's mass and measuring the average distance of Jupiter from the Sun. Answer: B 48) Which of the following best describes the origin of ocean tides on Earth? A) Tides are caused by the difference in the force of gravity exerted by the Moon across the sphere of the earth. B) The Moon's gravity pulls harder on water than on land, because water is less dense than rock. C) Tides are caused by the 23 1/2° tilt of the earth's rotational axis to the ecliptic plane. D) Tides are caused primarily by the gravitational force of the Sun. E) Tides are caused on the side of Earth nearest the Moon because the Moon's gravity attracts the water. Answer: A 49) The tides on Earth are an example of A) Newton's first law of motion. B) Newton's second law of motion. C) Newton's third law of motion. D) the universal law of gravitation. E) none of the above Answer: D 50) At which lunar phase(s) are tides most pronounced (e., the highest high tides)? A) first quarter B) new Moon C) full Moon D) both new and full Moons E) both first and third quarters Answer: D 51) At which lunar phase(s) are tides least pronounced (e., the lowest high tides)? A) first quarter B) new Moon C) full Moon D) both new and full Moons E) both first and third quarters Answer: E 10 Copyright By Jihao Zhou. 52) Suppose a lone asteroid happens to be passing relatively near Jupiter (but not near any of its moons), following a hyperbolic orbit as it approaches Jupiter. Which of the following statements would be true? A) Jupiter's gravity would capture the asteroid, making it a new moon of Jupiter. B) The asteroid's orbit around Jupiter would not change, and it would go out on the same hyperbolic orbit that it came in on. C) Jupiter would probably expel the asteroid far out into the solar system. D) The asteroid would slowly spiral into Jupiter until it crashed into the atmosphere. E) Any of these scenarios is possible. Answer: B 53) A basketball player jumps to make a basket, and remains in the air for a moment. A sportscaster, talking about the game, then remarks that she has "defied gravity." Which of the following accurately describes the situation? A) The player did stay in the air in spite of the Law of Gravitation, but a single counterobservation is not enough to warrant revisiting a theory that usually works. B) The player produced enough force with her legs to accelerate up into the air, and gravity brought her back down with an acceleration of 9 m/s2. C) The player only seemed to defy gravity, but part of the Universal Law of Gravitation makes an exception for basketball players. D) The player has defied gravity, so scientists must go back into the lab to refine their theory. Answer: B 54) Imagine we've discovered a planet orbiting another star at 1 AU every 6 months. The planet has a moon that orbits the planet at the same distance as our Moon, but it takes 2 months. What can we infer about this planet? A) It is more massive than Earth. B) It is less massive than Earth. C) It has the same mass as Earth. D) We cannot answer the question without knowing the mass of the star. E) We cannot answer the question without knowing the mass of the moon. Answer: B 4 True/False Questions 1) Speed and velocity are the same thing. Answer: FALSE 2) The Moon is constantly falling toward Earth. Answer: TRUE 3) If you are driving at 30 miles per hour and increase your speed to 60 miles per hour, you quadruple your kinetic energy. Answer: TRUE 11 Copyright By Jihao Zhou. 4 Short Answer Questions 1) Under what conditions is an object weightless? Answer: whenever it is in free-fall 2) State Newton's three laws of motion. Answer: 1. In the absence of a net force, an object moves with constant velocity. 2. Force = rate of change in momentum or mass times acceleration. 3. For every force there is an equal and opposite reaction force. 3) Give an example in which thermal energy might be converted to gravitational energy. Answer: A hot air balloon rises: as we heat the gas in a balloon, the internal pressure increases and the balloon expands. Therefore the density of the air inside decreases and when the average density of the entire balloon (balloon material plus basket plus air inside) becomes less than the density of air outside, the balloon rises, gaining gravitational energy. 4) Give an example in which kinetic energy can be converted to thermal energy. Answer: The brakes on a car: applying the brakes on a car slows it down through friction of the brake pads with the brake drums. The car slows down, losing kinetic energy, and the pads warm up, gaining thermal energy (try touching your wheels–but be careful because they can become very hot–after using your brakes for a long time, e., going down a steep mountain road).For the following questions, you may wish to refer to Newton's version of Kepler's third law: p2 = (Hint: You will not need a calculator for these problems.) 5) Imagine another solar system, with a star of the same mass as the Sun. Suppose there is a planet in that solar system with a mass of 2MEarth orbiting at a distance of 1 AU from the star. What (approximately) is the orbital period of this planet? Explain your answer. Answer: The orbital period of the planet would be approximately the same as that of the earth (1 year). Kepler's law considers only the sum of the object masses. In comparison with the mass of the star, the mass of the planet can be neglected. Thus, even though the planet is twice as massive as Earth, its orbit will be nearly the same as that of Earth. 6) Suppose a solar system has a star that is four times more massive than our Sun. If that solar system has a planet the same size as Earth, orbiting at a distance of 1 AU, what is the orbital period of the planet? Explain. Answer: From Kepler's law, we see that the period depends on the inverse square root of the object masses. Thus, if we have a star four times as massive as the Sun, the period of a planet orbiting at 1 AU will be half that of the earth, or 6 months. 13 Copyright By Jihao Zhou. 7) Suppose it takes 6 seconds for a watermelon to fall to the ground after being dropped from a tall building. If there were no air resistance, so that the watermelon would fall with the acceleration of gravity, about how fast would it be going when it hit the ground? Answer: Since the acceleration of gravity is about 10 m/s2, the watermelon gains 10 m/s of speed every second it is in the air. Therefore, the watermelon would be going 60 m/s when it hit the ground. 8) The Moon orbits Earth in an average of 27 days at an average distance of 384,000 kilometers. Using Newton's version of Kepler's third law p2 = determine the mass of Earth. You may neglect the mass of the Moon in comparison to the mass of Earth. Answer: Using the Moon's orbital period and distance, the mass of Earth is about 6 × 1024 kg. MEarth ≈ Making sure that we use appropriate units, we find: MEarth ≈ = 6 × 1024 kg 9) Explain how we can use Newton's version of Kepler's third law to measure the total mass of two stars in a binary system. Answer: By observing the stars with a telescope, you can measure how far they move apart from each other (their orbital distance, a) and how long it takes them to move around each other (their orbital period, p). Then you use the formula p2 = to derive the total mass of the two stars, M1 + M2. 10) Suppose a satellite is in a low-Earth orbit. Is it possible that the satellite will eventually fall to the ground? Why or why not? Answer: To fall to Earth, the satellite must lose some of its orbital energy. In low-Earth orbit, this can happen because the earth's atmosphere extends to high altitudes and exerts some atmospheric drag on the satellite. 14 Copyright By Jihao Zhou. 3) Momentum is defined as A) mass times velocity. B) mass times speed. C) force times velocity. D) mass times acceleration. Answer: A 4) Suppose you lived on the Moon. Which of the following would be true? A) Your weight would be less than your weight on Earth, but your mass would be the same as it is on Earth. B) Both your weight and your mass would be less than they are on Earth. C) Your mass would be less than your mass on Earth, but your weight would be the same as it is on Earth. D) Both your weight and your mass would be the same as they are on Earth. Answer: A 5) In which of the following cases would you feel weightless? A) while falling from a roof B) while parachuting from an airplane C) while accelerating downward in an elevator D) while walking on the Moon Answer: A 6) Which of the following statements is not one of Newton's Laws of Motion? A) What goes up must come down. B) The rate of change of momentum of an object is equal to the net force applied to the object. C) In the absence of a net force acting upon it, an object moves with constant velocity. D) For any force, there always is an equal and opposite reaction force. Answer: A 7) Newton's Second Law of Motion tells us that the net force applied to an object equals its A) mass times acceleration. B) mass times energy. C) momentum times velocity. D) mass times velocity. Answer: A 8) Suppose that two objects collide. Which of the following things is not the same both before and after the collision? A) the total temperature of the objects B) the total momentum of the objects C) the total angular momentum of the objects D) the total energy of the objects Answer: A 16 Copyright By Jihao Zhou. 9) When a spinning ice skater pulls in his arms, he spins faster because A) his angular momentum must be conserved, so reducing his radius must increase his speed of rotation. B) there is less friction with the air. C) there is less friction with the ice. D) there exists an unbalanced reaction force. Answer: A 10) The energy attributed to an object by virtue of its motion is known as A) potential energy. B) kinetic energy. C) radiative energy. D) mass-energy. Answer: B 11) Radiative energy is A) heat energy. B) energy from nuclear power plants. C) energy carried by light. D) energy of motion. Answer: C 12) Absolute zero is A) 0 Kelvin. B) 0° Celsius. C) 0° Fahrenheit. D) 100° Celsius. Answer: A 13) What does temperature measure? A) the average mass of particles in a substance B) the total potential energy of particles in a substance C) the total amount of heat in a substance D) the average kinetic energy of particles in a substance Answer: D 14) In the formula E=mc2, what does E represent? A) the mass-energy, or potential energy stored in an object's mass B) the kinetic energy of a moving object C) the radiative energy carried by light D) the gravitational potential energy of an object held above the ground Answer: A 17 Copyright By Jihao Zhou. 20) Which statement must be true in order for a rocket to travel from Earth to another planet? A) It must carry a lot of extra fuel. B) It must have very large engines. C) It must attain escape velocity from Earth. D) It must be launched from space, rather than from the ground. Answer: C 21) Approximately where is it currently high tide on Earth? A) on the portion of Earth facing directly toward the Moon and on the portion of Earth facing directly away from the Moon B) only on the portion of the Earth facing directly toward the Moon C) wherever it is currently noon D) anywhere that ocean water laps upon the shore Answer: A 4 Mastering Astronomy Concept Quiz 1) Which of the following represents a case in which you are not accelerating? A) driving in a straight line at 60 miles per hour B) going from 0 to 60 miles per hour in 10 seconds C) slamming on the brakes to come to a stop at a stop sign D) driving 60 miles per hour around a curve Answer: A 2) Suppose you drop a 10-pound weight and a 5-pound weight on the Moon, both from the same height at the same time. What will happen? A) Both will hit the ground at the same time. B) The 10-pound weight will hit the ground before the 5-pound weight. C) The 5-pound weight will hit the ground before the 10-pound weight. D) Both weights will float freely, since everything is weightless on the Moon. Answer: A 3) Why are astronauts weightless in the Space Station? A) because the Space Station is traveling so fast B) because the Space Station is constantly in free-fall around Earth C) because there is no gravity in space D) because the Space Station is moving at constant velocity Answer: B 4) A net force acting on an object will always cause a change in the object's A) momentum. B) speed. C) mass. D) direction. Answer: A 19 Copyright By Jihao Zhou. 5) Suppose you are in an elevator that is traveling upward at constant speed. How does your weight compare to your normal weight on the ground? A) It is greater. B) It is less. C) It is the same. D) You are weightless. Answer: C 6) The planets never travel in a straight line as they orbit the Sun. According to Newton's second law of motion, this must mean that A) the planets are always accelerating. B) the planets have angular momentum. C) the planets will eventually fall into the Sun. D) a force is acting on the planets. Answer: D 7) Suppose the Sun were suddenly to shrink in size but that its mass remained the same. According to the law of conservation of angular momentum, what would happen? A) The Sun would rotate faster than it does now. B) The Sun's rate of rotation would slow. C) The Sun's angular size in our sky would stay the same. D) This could never happen, because it is impossible for an object to shrink in size without an outside torque. Answer: A 8) Suppose you kick a soccer ball straight up to a height of 10 meters. Which of the following is true about the gravitational potential energy of the ball during its flight? A) The ball's gravitational potential energy is greatest at the instant it returns to hit the ground. B) The ball's gravitational potential energy is greatest at the instant when the ball is at its highest point. C) The ball's gravitational potential energy is always the same. D) The ball's gravitational potential energy is greatest at the instant the ball leaves your foot. Answer: B 9) Suppose you heat an oven to 400°F and boil a pot of water. Which of the following explains why you would be burned by sticking your hand briefly in the pot but not by sticking your hand briefly in the oven? A) The water can transfer heat to your arm more quickly than the air. B) The water has a higher temperature than the oven. C) The molecules in the water are moving faster than the molecules in the oven. D) The oven has a higher temperature than the water. Answer: A 20 Copyright By Jihao Zhou.
04 Testbank
Course: Astronomy (Sc/Nats 1740)
University: York University
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