Practice exam semester 1 physics Walk this Way Activity, Graph Sketching and Recognition, Sonic Ranger Lab: Use the graph to the right for q s 1-3 1. Which object(s) is (are) not moving? 2. Which change direction? 3. Which objects are accelerating? 4. According to the Sonic ranger graph example below, describe the motion of the person during the last segment of their graph plot. (assume toward detector is direction and moving away from the detector is + direction). Describe the motion of the person for segments A, B and C. Use the graph to the right for q s 5-8 5. Which objects have a change in direction 6. Which object(s) have constant velocity? 7. Which object(s) accelerate at least some of time? 8. Which object(s) are moving during the entire time plotted? Unit conversions: 9. An defensive lineman weighs 330 pounds. What is his mass in kg (given 2.2 pounds = 1 kg)? 330 lb 1 kg. 2.2 lb 10. 650 cm = 11. 26 g = Motion and Free Fall: 12. A friend challenges you to a reaction time test. She drops a meter stick and you catch it as fast as you can with your fingers. The best you could is to catch the meter stick after it fell 55 cm. What is your reaction time? t = 2(0.55 m) (9.8 m/s 2 = 0.34 s ) = 150 kg 13. If speedometer on a car reads a constant speed of 40 mi/hr, can you say the car must have a constant velocity? 14. What quantity describes how quickly you change your speed, or how quickly you change your direction 15. If you drop an object and it falls for 3 seconds, what speed would it be falling (ignore air resistance)? At the end of 3 s, it will fall 3s (9.8 m/s 2 ) = 29.4 m/s 16. If you drop an object and it falls for 3 seconds, how far did it fall (ignore air resistance)? d = 1/2 (9.8m/s 2 )(3) 2 = 44.1 m 17. If we take into account air resistance, does air resistance increase or decrease the acceleration of a falling object? 18. Which has more acceleration, a wolf increasing its speed from 0 to 30 m/s in 4 seconds or a coyote increasing its speed from 0 to 40 m/s in 5 seconds? a= (vf vi)/t => wolf = 7.5 m/s 2 coyote = 8 m/s 2 19. A tennis ball is thrown straight up. It takes 5 seconds for it to reach its maximum height. What was the maximum height the tennis ball reached? d=1/2gt 2 = 123 m Vectors/Projectiles 20. Suppose a ball rolls across a horizontal table top at 2.0m/s. It rolls off the edge of the table and falls to the floor below. How fast was the ball moving horizontally while falling through the air (ignore air resistance)? 21. How long (in terms of time) did it take for the ball to fall to the floor after it rolled off the table? Given: table height is 0.4 m (ignore air resistance)? 2 (0.4 m) t = 9.8 m/s 2 = 0.29 s 22. If a ball has a horizontal speed of 3.0 m/s before it leaves the edge of a horizontal table top, how far from the table (in the horizontal direction) will the marble land? Given time in the air is 0.40 seconds. d = vt = 1.2 m
23. If we ignore air resistance, and you throw a baseball 15m/s in the horizontal direction (that is the speed just as it leaves your hand) to your friend, the catching speed (in the horizontal direction) will be 24. A ball is launched into the air. The ball s total air time is 3.0 seconds. What was the time it took for the ball to reach the peak (time up)? 25. What is the vertical velocity (V y ) of the ball at the peak of its flight? 26. What is the acceleration of the ball at the peak of its flight? 27. A monkey has a habit of dropping from a tree the moment that a banana leaves the muzzle of a cannon. The zookeeper is faced with the dilemma of where to aim the banana cannon in order to hit the monkey. If the monkey lets go of the tree the moment that the banana is fired, then where should she aim the banana cannon in order to hit the monkey as it falls? 28. Suppose you throw a football to your friend 10 meters away. Which component(s) of its motion remains constant throughout its flight? 29. Suppose you throw a football to your friend 30 meters away. Which component(s) of its motion determines the time the football is in the air? 30. Two pennies are launched from a table, one penny drops straight down and the other initially launches from the edge of the table in a horizontal direction. Which penny will hit the floor first? 31. Suppose a truck with a cannon in the back is driving at 20 m/s to the east. If a soccer ball is shot out of the cannon at 20 m/s to the east, what would the speed of the ball appear to be relative to person at rest standing along the side of the road where the ball is shot? 40 m/s What would it appear if the ball to the person at rest if it was shot to the west? 0 32. A marble rolls down a ramp on top of a table. The marble rolled horizontally for 1..0 m after it went down the ramp and it took 3.0 seconds to travel that horizontal distance. If the table is 0.75 meters tall, how far from the bottom of the table will the marble land when it rolls off the table? step 1: v=d/t = 0.33 m/s step 2: t = (2d/g) = 0.39 s step 3: d = vt = (0.33m/s)(0.39s) = 0.129 m 33. (October sky) If we ignore air resistance at what angle (in degrees) should a projectile be launched for maximum horizontal range? 45 o Questions 37-45 refer to this situation: A ball is thrown at an angle giving it an initial vertical velocity of 15 m/s and an initial horizontal velocity of 25m/s. It is an airless environment. 34. What is the vertical component of the velocity at the peak of the path? 35. What is the vertical component of the velocity just before the ball is caught? 36. What force(s), if any, are affecting the vertical motion of the ball? 37. What is the horizontal component of the velocity at the peak of the path? 38. What is the horizontal component of the velocity just before the ball is caught? 39. What force(s), if any, are affecting the horizontal motion of the ball? 40. What is the acceleration just after it leaves the first guy s hand? 41. What is the acceleration at the peak of the path? 42. What is the acceleration just before it is caught? 43. Referring to the projectile trajectories shown at right, which projectile would have had the longest flight time? 44. Referring to the projectile trajectories shown at right, which projectile would have had the highest initial vertical velocity? 45. Referring to the projectile trajectories shown at right, which projectile would have had the highest
horizontal velocity? 46. Referring to the projectile trajectories shown at right, which projectile would have had the greatest acceleration on the fall back down? 47. Referring to the projectile trajectories shown at right, which projectile would have had the highest initial vertical velocity? (ignore air resistance) 48. Referring to the projectile trajectories shown at right, which projectile would have had the highest horizontal velocity? (ignore air resistance) 49. Which projectile would have had the longest flight time? (ignore air resistance) 50. A hammer and a feather are both dropped from a height of 1.0 m on the moon, where there is no air resistance. Which hits the ground first? Newton's Laws 51. When attempting to stop your car on a wet road, the reason you shouldn't lock your brakes (make the tires stop rolling and have them slide across the road s surface) is: (explain in terms of kinetic and static friction). 52. True or False: The more an object weighs the more friction it will experience on a given surface. 53. Randy is pulling Suzie in a wagon with a force of 250 N. The frictional force between the wagon and the floor is 40 N. What is the net force? 40N 250 N = 210 N 54. What is Suzie s mass if it takes a net force of 65 N to accelerate at 0.9 m/s 2? 65 N = m (0.9 m/s 2 ) m = 72 kg The following information is used to answer 58-59: A 200 kg bundle of supplies is dropped from a helicopter that is hovering 1200 m above the ground. A parachute is attached to the bundle and it supplies air resistance so that bundle has reached terminal velocity as it is falling. 55. What would be the upward force due to air resistance at terminal velocity? weight = mg = 1960 N 56. What would be the acceleration of the bundle at terminal velocity? 57. A 1000 kg boat accelerates at 12.7 m/s 2. What is the net force acting on the boat? F net = ma = (1000 kg)(12.7 m/s 2 ) = 12,700 N 58. Suppose the net force on the boat is 50,000 N. If the drag (friction on the boat as it moves through the water) is 1000N and air resistance is 2000 N, what is the forward force supplied by the motor of the boat? 1000N? = 50,000 N? - 3000 = 50,000 so? = 53,000 N 2000 N 59. The tendency for an object in motion maintain its state of motion when no outside force acts on it is called: 60. A red dog is laying on a park bench sleeping in the summer sun. The dog has a mass of 25 kg. How much does he weight (hint: answer has units of Newtons)? weight = mg = 245 N 61. If the net force on a shopping cart is tripled, and its mass is constant, what happens to its acceleration? 62. If you doubled the mass of a cart and keep the net force applied on it constant, what happens to its acceleration (mass is constant & ignore friction acting on the cart)? 63. Which would have the least inertia? a large train at rest or a slow moving car or a speeding bullet 64. What force is needed to keep Elmo moving on his bike at a constant speed in a straight line if it has 40 N friction acting on it and he has a mass of 30 kg?. 65. Shelly wants to lift a 220 N dog over her head with a 20 N net force acting on the dog as she lifts it. How much upward force must she apply to do this? 66. The force of gravity is 5 times as great on a 5 kg pumpkin as it is on a 1 kg melon. Why does the5 kg pumpkin not fall with 5 times the acceleration as the melon?
67. The sketch shows a top view of a rock being whirled at the end of a string (clockwise). If the string breaks, the path of the rock is 68. Suppose a big, 3000 kg truck has a head-on collision with a small, 1000 kg sports car. A) Which vehicle would have the most force applied to it? B) Which vehicle would accelerate the most due to the collision? Given: During a football game, a big (massive), fast football player collides with a smaller (less massive), slower football player. 69. Is the following statement true(a) or false (b)?: During the collision, the bigger football player will apply a smaller force to the smaller football player than the smaller football player will apply to the bigger football player. Bridges 70. Suppose your hand pushes on the top of the triangle. Which triangle below shows the correct force vectors. 71. For a truss bridge, what forces do the bottom members experience? 72. For the towers in a suspension bridge, which force is involved? 73. True or False: The bottom part of a beam or plank bridge undergoes compression when a load is applied to it. 74. What type of force does an arch bridge experience the most? 75. For the bridges we build and test, which force is most likely to cause a wood stick to break? 76. For the cables in a suspension bridge, which force is involved? Momentum ch. 7 77. Which has more momentum, a sports car moving at 20 miles per hour or the same sports car moving at 50 miles per hour? 78. How are momentum and inertia similar and different? 79. Impulse equals: (give two definitions) 80. Explain how changing the time of impact for a collision affects the force of the collision 81. A bug and the windshield of a fast-moving car collide. How do the forces compare? 82. Describe an elastic and an inelastic collision, giving an example of each 83. Describe a recoil and give an example. Impulse Notes and Egg Drop Activity: 84. Why do karate experts bounce their hands off of boards in order to break them? 85. When striking a ball with a bat, why do you follow through explain in terms of time, force, and change in momentum. 86. During an egg drop experiment, a student added crumpled-up paper around the egg. Explain in terms of time, force, and change in momentum. 87. Suppose you drop two identical watermelons off of a high dive platform 10 meters high. If one melon is stopped by concrete and the other melon is stopped by water, the melon that hits water doesn t break. explain in terms of time, force, and change in momentum. 88. A car with a mass of 1000 kg moves at 12 m/s. The car comes to a halt. What impulse does the car experience? impulse = p final p initial = 0 - (1000 kg x 12 m/s) = -12,000 89. A car with a mass of 1000 kg moves at 12 m/s. What braking force is needed to bring the car to a halt in 4.0 seconds? F = (p final p initial ) / t = -12,000 / 4.0 = -3000 N
For 90-100, complete a MVP table for the following scenario: A bullet and rifle are at rest. the rifle is shot, the bullet travels at a speed of 75 m/s to the right. The bullet has a mass of.02 kg. The gun has a mass of 1.8 kg. gun gun 1.8 kg 0 REMOVED 1.8 kg - 0.83m/s REMOVED bullet 0.2 kg 0 REMOVED bullet 0.02kg 75m/s REMOVED 0 0 For q s 101 114, complete the MVP table (with units) for the following scenario: A large Ford truck traveling east at 8 m/s hits a deer moving 2 m/s to the west. An elastic collision occurs. The mass of the truck is 2000 kg and the mass of the deer is 80 kg. the collision the truck moves 7 m/s towards the east. Truck Truck 2000 kg 8 m/s REMOVED 2000 kg 7 m/s REMOVED Deer 80 kg -2 m/s REMOVED Deer 80 kg 23 m/s REMOVED 15,840 15,840 For 115 124 complete the MVP table (with units) for the following scenario: A 80 kg shark swimming at 5 m/s to the right swallows a 3 kg mackerel that is swimming 2 m/s to the left. Hint: this is an inelastic collision Shark Shark 80 kg 5 m/s REMOVED Mackerel 3 kg - 2 m/s REMOVED Mackerel 394 83 kg 4.75 m/s 394