What Class of Motion, Natural or Violent, Did Aristotle Attribute to Motion of the Moon

1.What class of motion, natural or violent, did Aristotle attribute to motion of the Moon? The two main classes that Aristotle divided motion into are natural motion and violent motion. 2. What state of motion did Aristotle attribute to Earth? Aristotle believed that the Earth's state of motion was at rest. 3. What relationship between the Sun and Earth did Copernicus formulate? Copernicus believed that Earth circles the Sun. 4. What did Galileo discover in his legendary experiment on the Leaning Tower of Pisa? Galileo discovered that heavier objects in freefall did not fall faster than lighter objects. Expressed in modern language, he discovered that an object's acceleration near the Earth's surface is independent of its mass. 5. What did Galileo discover about moving bodies and force in his experiments with inclined planes? Galileo discovered by experiment and reasoning that a moving object will continue in motion forever, in the absence of friction or other opposing forces. 6. Is inertia the reason for moving objects maintaining motion or the name given to this property? Inertia is the name given to the property that "objects maintain their motion." 7. How does Newton’s first law of motion relate to Galileo’s concept of inertia? Newton’s First Law is a restatement of the concept of inertia that Galileo originated. 8. What type of path does a moving object follow in the absence of a force? In the absence of a net force, a moving object moves in a straight line at the same speed forever. 9. What is the net force on a cart that is pulled to the right with 100 pounds of force and to the left with 30 pounds of force? The net force is 70 pounds to the right. 10. Why do we say that force is a vector quantity? Because the complete force description requires both, magnitude and direction. 11. According to the parallelogram rule, what quantity is represented by the diagonal of a constructed parallelogram? I believe a diagonal of a parallelogram represents the sum of two vectors which are used to form the parallelogram. 12. What is the resultant of a pair of 1-pound forces at right angles to each other? A pair of one-pound forces at right angles have a resultant of two square root of a pound, along the line that is halfway between the two forces. 13. Consider Nellie hanging at rest in Figure 2.11. If the ropes were vertical, with no angle involved, what would be the tension in each rope? I believe the tension would be half of what Nellie weighs. 14. Can force be expressed in units of pounds and also in units of newtons? Yes, because the force or 5 newtons is somewhere around 1.1 pounds. 15. What is the net force on an object that is pulled with forces of 80 newtons to the right and 80 newtons to the left? Zero because it cancels out... not 100% sure. 16. What is the net force on a bag pulled down by gravity with a force of 18 newtons and pulled upward by a rope with a force of 18 newtons? Also zero, the forces still cancel out. 17. What does it mean to say something is in mechanical equilibrium? An object in mechanical equilibrium simply means the net force on it is zero. 18.State the equilibrium rule for forces in symbolic notation. EF=0 … I know these aren’t the correct symbols but they ae the best symbols I could come up with. 19. How many newtons of support force does the table provide? What is the net force on the book in this case? The table should be giving 15 newtons of support, and the books net force is 0. 20. When you stand at rest on a bathroom scale, how does your weight compare with the support force by the scale? Support force exerted on you by the scale is upward, of the same magnitude as your weight. 21. A bowling ball at rest is in equilibrium. Is the ball in equilibrium when it moves at constant speed in a straight-line path? Yes, it just means that the state has no change. 22. What is the net force on an object in either static or dynamic equilibrium? Net force on an object in equilibrium is always zero. 23. If you push on a crate with a force of 100 N and it slides at constant velocity, how great is the friction acting on the crate? 10 times as much… 100 newtons. 24. What concept was not understood in the 16th century when people couldn’t conceive of a moving Earth? Inertia, it was not excepted because it did not make sense to the public. 25. A bird sitÝng in a tree is traveling at 30 km/s relative to the faraway Sun. When the bird drops to the ground below, does it still move at 30 km/s, or does this speed become zero? The birds speed does not change. It is still moving at the same speed no matter what. 26. Stand next to a wall that travels at 30 km/s relative to the Sun. With your feet on the ground, you also travel at the same 30 km/s. Do you maintain this speed when your feet leave the ground? What concept supports your answer? Yes, you will maintain the same speed, this is supported by the concept of inertia. 28. Henry Heavyweight weighs 1200 N and stands on a pair of bathroom scales so that one scale reads twice as much as the other. What are the scale readings? 400 Newtons and 800 Newtons 30. A different scaffold that weighs 400 N supports two painters, one 500 N and the other 400 N. The reading in the left scale is 800 N. What is the reading in the right-hand scale? 500 Newtons I believe 32. Rank the net forces on the blocks from least to most in the four situations, A, B, C, and D. CABD 34. Three pucks, A, B, and C, are shown sliding across ice at the noted speeds. Air and ice friction forces are negligible. (a) Rank the forces needed to keep them moving, from greatest to least. (b) Rank the forces needed to stop them in the same time interval, from greatest to least. (a) There is no force needed (b) C B A 36. Nellie hangs motionless by one hand from a clothesline. Which side of the line, a or b, has the greater tension? Side A should have the larger tension 38. A ball rolling along a floor doesn’t continue rolling indefinitely. Is this because it is seeking a place of rest or because some force is acting upon it? If the latter, identify the force. A rolling ball stops rolling because of a net force acting on it. 40. What Aristotelian idea did Galileo discredit in his fabled Leaning Tower demonstration? Galileo discredited the Aristotelian falling-body idea, that heavier bodies would fall at a rate proportional to their weight. 42. Was it Galileo or Newton who first proposed the concept of inertia? Galileo 44. A space probe may be carried by a rocket into outer space. What keeps the probe moving after the rocket no longer pushes it? Nothing it continues to move on its own. 46. In tearing a paper towel or plastic bag from a roll, why is a sharp jerk more effective than a slow pull? The large inertia of the roll helps it to stay still. The sharp jerk is a bigger force, which exceeds the breaking strength of the paper. 48. In terms of Newton’s first law (the law of inertia), how does a car headrest help to guard against whiplash in a rear-end collision? It keeps your head from being jerked and turning sideways. 50. Consider a pair of forces, one having a magnitude of 20 N and the other a magnitude of 12 N. What is the strongest possible net force for these two forces? What is the weakest possible net force? 32 Newtons, and 8 newtons 52. Which of the following are scalar quantities, which are vector quantities, and which are neither? (a) force; (b) age; (c) acceleration; (d) temperature. A and C are vector quantities. B and D scalar quantities. 54. Which is more likely to break: a hammock stretched tightly between a pair of trees or one that sags more when you sit on it? A tightly stretched hammock 56. The rope supports a lantern that weighs 50 N. Is the tension in the rope less than, equal to, or greater than 50 N? Less than 50 Newtons. 58. The rope of Exercise 56 is repositioned as shown and still supports the 50-N lantern. Is the tension in the rope less than, equal to, or greater than 50 N? Greater than 50 Newtons. 60. Can an object be in mechanical equilibrium when only a single nonzero force acts on it? Explain. No because there is still a force being moved upon it. 62. Your friend sits at rest on a chair. Can you say that no force acts on her? Or is it correct to say that no net force acts on her? It is correct to say that no net force acts on your friend, but it would be incorrect to say that there are no forces at all. 64. Harry the painter swings year after year from his bosun’s chair. His weight is 500 N and the rope, unknown to him, has a breaking point of 300 N. Why doesn’t the rope break when he is supported as shown at the left? One day, Harry is painting near a flagpole, and, for a change, he ties the free end of the rope to the flagpole instead of to his chair, as shown at the right. Why did Harry end up taking his vacation early? In the right diagram, Harry is now supported by only one rope, and if he is to remain in equilibrium, the tension must equal his weight, 500 N. Since this is above the breaking point of the rope, 300 N, it breaks and Harry gets to take his vacation early. 66. If the strong man in the preceding exercise exerts a downward force of 800 N on the rope, how much upward force is exerted on the block? 800 Newton 68. How many significant forces act on a book at rest on a table? Identify the forces. 2.) the weight of the book and the table 70. As you stand on a floor, does the floor exert an upward force against your feet? How much force does it exert? Why aren’t you moved upward by this force? Yes, the floor exerts an upward force on your feet, same as your weight. Gravity. 72. An empty jug of weight W rests on a table. What is the support force exerted on the jug by the table? What is the support force when water of weight w is poured into the jug? For the empty jug, the support force is W. After the water is added to the jug, the support force is W + w. 74. In order to slide a heavy cabinet across the floor at constant speed, you exert a horizontal force of 600 N. Is the force of friction between the cabinet and the floor greater than, less than, or equal to 600 N? Defend your answer. = 600 Newtons 76. Two people each pull with a force of 300 N on a rope in a tug-of-war. What is the net force on the rope? How much force is exerted on each person by the rope? It would be zero Newtons and 300 Newtons. 78. A child learns in school that Earth is traveling faster than 100,000 kilometers per hour around the Sun and, in a frightened tone, asks why we aren’t swept off. What is your explanation? We stay on the Earth because we have the same speed as the Earth beneath us, just as we don't have to worry about being swept off a jet plane or being pressed to the back of the plane when it is flying at constant speed. 80. Your friend says that inertia is a force that keeps things in their place, either at rest or in motion. Do you and your discussion partners agree? Why or why not? I would have to disagree because they simply are wrong. That is not what inertia is. 82. Suppose that you’re in a moving car and the motor stops running. You step on the brakes and slow the car to half speed. If you release your foot from the brakes, will the car speed up a bit, or will it continue at half speed and slow due to friction? Defend your answer with your discussion partners. The car will continue to move at half the speed, then it will slow down due to the friction. 84. Each bone in the skeletal chain of bones forming your spine is separated from its neighbors by disks of elastic tissue. What happens, then, when you jump heavily onto your feet from an elevated position? (Hint: Think about the hammerhead in Figure 2.5.) Discuss why you think you are a little taller in the morning than at night. If you jump heavily onto your feet from an elevated position, your spine will tend to compress. At the end of the day, after your body has jostled up and down from walking, and felt the effects of gravity, you will be a tiny bit shorter. 86. Consider the normal force on a book at rest on a tabletop. If the table is tilted so that the surface forms an inclined plane, will the magnitude of the normal force change? If so, how? Yes, magnitude of the regular force will change as the table is tilted. It decreases. 88. Before the time of Galileo and Newton, some learned scholars thought that a stone dropped from the top of a tall mast of a moving ship would fall vertically and hit the deck behind the mast by a distance equal to how far the ship had moved forward while the stone was falling. In light of your understanding of Newton’s first law, what do you think about this? I don’t think the stone should land behind the mast. 90. If you toss a coin straight upward while riding in a train, where does the coin land when the motion of the train is uniform along a straight-line track? When the train slows while the coin is in the air? The coin will land in your hand if the train maintains a constant straight line. If the train slows down, the coin will land in front of you instead. 92. The smokestack of a stationary toy train consists of a vertical spring gun that shoots a steel ball a meter or so straight into the air—so straight that the ball always falls back into the smokestack. Suppose the train moves at constant speed along the straight track. Do you think the ball will still return to the smokestack if shot from the moving train? What if the train gains speed along the straight track? What if it moves at a constant speed on a circular track? Discuss why your answers differ. 1st The ball falls back into the smokestack. 2nd it misses the smokestack. 3rd case because the train does not keep moving in a straight line at constant speed. Answers will differ depending on personal train experiences.