Unit 3, Chapter 2 Quiz

Transcription

1 Unit 3, Chapter 2 Quiz Name Date Class Part I: Multiple Choice 1. When does a planet have gravitational interactions with other objects close to it? a) Only when the planet is built from magnetic material. b) Only when the planet rotates. c) Only when the planet has an atmosphere. d) None of the other options is correct. 2. A gravitational interaction is an interaction a) with the Earth s magnetic field. b) between any pair of masses. c) with the rotation of the Earth. d) with air pressure from the Earth s atmosphere. 3. You and your friend are standing on the floor beside each other, without touching. There is a gravitational interaction a) between you and your friend that keeps you apart. b) between you and your friend that causes you to slide towards each other. c) There is only a gravitational interaction between you and the Earth. d) between you and your friend, but it is hard to notice because it is so small. 4. Two coconuts of different masses are falling from a tree to the ground. Which of the following sentences is correct? a) The Earth has a gravitational interaction with the coconuts, but it doesn t exert any forces on them. The only force acting on the coconuts is drag. b) The force the Earth exerts on each coconut doesn t change as the coconuts get closer to the ground. c) The force the Earth exert on each coconut is the weight of the coconut. d) The force the Earth exerts on the heavier coconut is weaker than the force the Earth exerts on the lighter coconut. InterActions in Physical Science 1

2 CHAPTER 2 GRAVITATIONAL INTERACTIONS 5. Identify the forces acting on a tossed coin and their directions. Ignore drag. a) The force of gravity pulls down on the coin both while the coin is going up and while it is going down. b) The force of gravity pulls up on the coin while the coin is going up and pulls down while the coin is going down. c) There is no force on the coin while it is going up, and the force of gravity pulls down on the coin while it is going down. d) The answer depends on whether the coin is tossed in the northern hemisphere or in the southern hemisphere. 6. In a science fiction movie, an astronaut lands on a planet, nails down a pole and from the pole hangs a small ball attached to a string (see figure). How will the pendulum hang? a) In position A b) In position B c) In position C d) None of the other options are correct. A B C 7. What is the direction of the force exerted by the Earth on the Moon? a) A b) B c) D d) C Earth D C B A Moon 8. In order for an object to move in a circle, it needs to have a force pushing or pulling it inward all the time. What makes an artificial satellite orbit around the Earth? a) It has a motor that gives it a push toward the center of the circle (the center of the Earth). b) Gravity pulls it toward the center of the circle and a motor gives it a push outward, so that it doesn t fall to the Earth. c) Gravity pulls it toward the center of the circle (that is, the center of the Earth). d) The motor gives it a push inward when it s first put in orbit, and then it just keeps moving around. 2 UNIT 3: INTERACTIONS AND FORCES

3 Unit 3, Chapter 2 Quiz 9. As a parachutist falls with his parachute open, the downward force from the gravitational interaction is the same strength as the upward force of the drag interaction. The parachutist a) moves at a constant speed. b) slows down. c) immediately starts slowing to a stop. d) speeds up. 10. A raindrop falls through the air. At the beginning of the motion it speeds up, but after some time it moves at constant speed. How does the drag force on the raindrop change as the drop speeds up? a) The drag force increases as the raindrop speeds up. b) The drag force decreases as the speed of the drop increases. c) The drag force is constant during the fall. d) The drag force is always equal to gravity. East Force exerted by air on parachutist (parachutist) Force exerted by Earth air on parachutist West 11. Tim is skating on a frozen pond with his brother Harry. Tim is sliding west on the ice. The ice exerts a friction force of 30 N that opposes Tim's motion. A stiff breeze blowing toward the east exerts a force of 130 N on Tim. Then Harry bumps into Tim from behind, giving him a westward shove of 320 N. What is the strength and direction of the unbalanced force on Tim when Harry bumps him? a) Strength is 160 N, direction is east. b) Strength is 160 N, direction is west. c) Strength is 220 N, direction is east. d) Strength is 220 N, direction is west. Harry Tim force of wind on Tim friction force on Tim force of Harry on Tim 12. Sandy places a strong magnet underneath a table, directly below an iron cube that weighs 2.2 N. The magnet pulls down on the iron cube with a force of 6.6 N. The iron cube does not budge because the table exerts a force on the cube that balances the other forces. What is the strength and direction of the balancing force exerted by the table? a) Strength is 4.4 N, direction is down b) Strength is 3.0 N, direction is down c) Strength is 8.8 N, direction is up d) Strength is 4.4 N, direction is up table iron cube magnet InterActions in Physical Science 3

4 CHAPTER 2 GRAVITATIONAL INTERACTIONS 13. Rachel sleeps in her bed, dreaming of taking rocket trips to Mars. What type of force balances her weight and prevents her from dropping through the bed? a) Frictional force b) Drag force c) Gravitational force d) Compression force 14. A boat floats motionless on the surface of a lake. The boat has a weight of 35,000 N. The part of the boat below water is 40% of the boat s volume, but 60% of the boat s mass. What is the weight of the water displaced by the boat? a) 28,000 N b) 14,000 N c) 21,000 N d) 35,000 N 60% of volume, 40% of mass 40% of volume, 60% of mass 15. Mercury, also known as quicksilver, is a poisonous liquid metal with a density of 13.6 g/cm 3. Which of the following metals would sink in mercury? a) Silver (density = 10.5 g/cm 3 ) b) Lead (density = 11.4 g/cm 3 ) c) Gold (density = 19.3 g/cm 3 ) d) Silver, gold and lead would all sink in mercury. 16. A pendulum is a system that has both kinetic (motion) energy and potential energy. Consider a "washer" pendulum like the ones you studied in Unit 1. In the diagram, the washer swings between Position A and Position E. At which position(s) does the washer have the most kinetic energy? a) Positions A and E b) Positions B and D c) Position C d) Positions B, C and D A B C D E 4 UNIT 3: INTERACTIONS AND FORCES

5 Unit 3, Chapter 2 Quiz 17. As it orbits Earth, the Moon is not always the same distance from Earth. Its distance varies from 363,000 km to 406,000 km, with an average of 384,000 km. The Moon's speed also varies. The Moon moves fastest when it is closest to Earth, and is slowest when it is farthest away. At what distance is the potential energy of the Earth-Moon system at its maximum? a) 363,000 km b) 406,000 km c) 384,000 km d) The potential energy is always the same. Moon 406,000 km 363,000 km Earth average distance = 384,000 km 18. Which planet-moon system has the greatest gravitational potential energy? The planets and moons are listed below in order from smallest mass to largest mass. Planets: (smallest mass) Mars, Earth, Jupiter (largest mass) 400,000 km Moons: (smallest mass) Phobos, Io and the Moon (about tied for largest mass) a) Mars and Phobos (separated by 9000 km) Jupiter b) Earth and Moon (separated by about 400,000 km) c) Jupiter and Io (separated by about 400,000 km) d) About tied between the Jupiter-Io and Earth-Moon systems. 400,000 km Earth Mars figure is not to scale 9,000 km 19. What is the difference between a planet and a dwarf planet? a) Unlike dwarf planets, planets are always round. b) Unlike dwarf planets, planets dominate their orbital neighborhoods. c) Dwarf planets are planets that are smaller than Mercury. d) Dwarf planets are icy worlds found beyond Neptune's orbit, farther than any planets. 20. Which option below correctly lists characteristics of the gas-giant planets in the Solar System? a) Thick atmospheres of oxygen and nitrogen; rocky surfaces; few or no moons. b) Thick atmospheres of hydrogen and helium; rings; many moons. c) Thick atmospheres of oxygen and nitrogen; rings; many moons. d) Thick atmospheres of hydrogen and helium; rocky surfaces; few or no moons. InterActions in Physical Science 5

6 CHAPTER 2 GRAVITATIONAL INTERACTIONS 21. The Sun accounts for approximately of the mass in the Solar System. a) 99% b) 25% c) 50% d) 75% 22. Uranus is much larger than Mercury and also reflects more sunlight (51% for Uranus compared to 11% for Mercury). Mercury is visible to the eye and has been known to people on Earth for thousands of years. Uranus was only discovered by telescope in Why can humans see Mercury using only their eyes, while they need telescopes to look at Uranus? a) Mercury is made so hot by the Sun that it glows. b) Mercury is much closer to Earth than Uranus. c) Mercury shines by its own light, not just by light reflected from the Sun. d) We can see Mercury as a black speck on the Sun when it crosses between Earth and the Sun. 23. What is the definition of a light year (ly)? a) the time that it takes light to travel in one year. b) the distance between Earth and the Sun. c) the distance that light travels in one year. d) three hundred sixty-five light days. 24. All planets and dwarf planets orbit the Sun in elliptical orbits, but some orbits are nearly circular while others are extremely elliptical. In a nearly circular orbit, a body's distance from the Sun varies only by a couple percent. In a highly elliptical orbit, a body's distance from the Sun can vary by more than 100%. Which planet or dwarf planet below has the most circular orbit? The minimum and maximum distance from the Sun are given. Highly elliptical orbit Nearly circular orbit Planet Planet Sun Sun a) Mercury: min AU, max AU b) Pluto: min AU, max AU c) Earth: min AU, max AU d) Eris: min AU, max AU 6 UNIT 3: INTERACTIONS AND FORCES

7 Unit 3, Chapter 2 Quiz 25. While it is forming, one type of body uses its gravity to sweep up nearly all the gas and debris in its orbit about the central star (like the Sun). This type of body is called a a) planet. b) dwarf planet. c) comet. d) moon. 26. When a large cloud in the space between the stars collapses to form a solar system, what kind of shape does it take? a) A sphere or ball with a dense center. b) A football or egg-like shape with a dense center. c) A blob with a dense center. d) A disk with a dense center. 27. What distinguishes planets and dwarf planets from other bodies that orbit the Sun? a) Planets and dwarf planets have moons, rings or both. b) Planets and dwarf planets dominate their orbital neighborhoods. c) Planets and dwarf planets have atmospheres. d) Planets and dwarf planets have enough gravity to make themselves round. (Continued) InterActions in Physical Science 7

8 CHAPTER 2 GRAVITATIONAL INTERACTIONS Part II: Analysis and Explanation Use How To Write an Analysis and Explanation to help you answer Question 28. In your analysis, you should identify the interacting objects, the type of interaction, and draw an force arrows diagram. Write your explanation using complete sentences. Check that your analysis and explanation are good using the criteria in How To Evaluate an Analysis and Explanation. 28. Benjamin is playing with his little brother. They are trying to throw a ball as high as they can. When Benjamin throws the ball, he observes it slows down all the way up. Task: Analyze and explain why the ball slows down during its rise. Neglect the drag force. Force exerted by Earth on ball Analysis: Force Diagram: Explanation: 8 UNIT 3: INTERACTIONS AND FORCES