6. Momentum is not conserved in all collisions. 7. The direction of the net force and the direction of the impulse are always the same.

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1 Modified True/False Indicate whether the sentence or statement is true or false. If false, change the identified word or phrase to make the sentence or statement true. 1. Linear momentum is a scalar quantity. _ 2. The impulse is always in the same direction as the net force. _ 3. The average force accurately represents the actual force during a collision. 4. If the net force acting on a system of objects is zero, the linear momentum of the system is conserved for any number of objects. _ 5. In a one-dimensional linear momentum question, only the speed is important to know for colliding objects. 6. Momentum is not conserved in all collisions. _ 7. The direction of the net force and the direction of the impulse are always the same. _ 8. A single train car loaded with sand travels by itself along a horizontal frictionless track at a constant speed. A hole is punctured in the bottom of train and the sand slowly leaks out causing the train car to speed up. _ 9. Two blocks of different mass are attached by a string and slide along a horizontal frictionless surface at a constant speed. When the string is cut, the speed of the larger block will stay the same. _ 10. A system consists of a sliding wooden block on a wooden plank. The plank is mounted on frictionless wheels. Friction causes the block to slow down and stop, so momentum of the system is not conserved. _ 11. It is possible that an object can receive a larger impulse from a small force than from a large force. _ 12. During a collision of a bullet and a wooden block, the force of friction can be neglected because the interaction is so brief. _ 13. When you triple the velocity of an object of constant mass, you also triple the momentum. _ 14. Momentum cannot be used during car collisions that involve cars with crumple zones. _ 15. Knowledge of momentum has not reduced the number of deaths in vehicular accidents in the past 10 years. _ Multiple Choice Identify the letter of the choice that best completes the statement or answers the question. 16. A 5.0-kg cat travelling at 1.3 m/s [E] has a momentum of a. 6.5 m/s [E] d. 3.8 m/s [W] b. 6.5 m/s [W] e. none of the above c. 3.8 m/s [E]

2 17. A bobsleigh and its riders have a combined mass of 598 kg. They cross the finish line with a velocity of 125 km/h [forward]. The momentum of the team and the bobsleigh at the finish line is a kg m/s [forward] d kg m/s [forward] b kg m/s [forward] e kg m/s [forward] c kg m/s [forward] 18. A bullet with a momentum of 2.8 kg m/s [E] is travelling at a speed of 187 m/s. The mass of the bullet is a g d. 67 g b g e. not enough information c. 15 g 19. During collisions, it is often acceptable to ignore the force of gravity on an object. This is because a. the time the other forces act is so short that we can ignore the force of gravity b. the force of gravity is always acting on the object and we only consider change c. the object may be in space and the gravitational force does not exist d. the collision is often perpendicular to the force of gravity, so F g does not play a role e. the force of gravity is insignificant compared to the other forces acting on the object 20. A net force of 12 N changes the momentum of a 250-g ball by 3.7 kg m/s. The force acts for a s d. 3.2 s b s e. 44 s c. 1.2 s 21. A 2200 kg car starts from rest and speeds up to 12 m/s in 5.2 s. The net force acting on the car is a N d N b N e N c N 22. A car with a mass of 1800 kg slows from 42 km/h [E] to 28 km/h [E]. The impulse from the brakes is a N s [E] d N s [W] b N s [W] e N s [W] c N s [E] 23. A 1.5-kg bird is flying at a velocity of 18 m/s [22º above the horizontal]. The vertical component of its momentum is a. 10 m/s [up] (2 significant digits) d. 17 m/s [up] b. 6.7 kg m/s [up] e. none of the above c. 25 kg m/s [up] 24. A 1.5-kg bird is flying west at a velocity of 18 m/s [22º above the horizontal]. The horizontal component of its momentum is a. 10 m/s [W] (2 significant digits) d. 17 m/s [W] b. 6.7 kg m/s [W] e. 17 kg m/s [E] c. 25 kg m/s [W] 25. A bullet with a mass of 28 g is fired from a 2.8-kg gun that is stationary, but free to recoil. After the bullet is fired, the gun is observed to be moving at 1.4 m/s [left]. The velocity of the bullet is a. 140 m/s [left] d. 71 m/s [left] b. 140 m/s [right] e. 71 m/s c. 71 m/s [right] 26. A shell is fired from a gun mounted on a battleship. Which of the following statement is NOT true? a. There will be a force to push the boat in the opposite direction of the shell. b. The recoil spring on the barrel is to minimize the force on the deck of the ship. c. Neglecting fluid friction, the momentum of the boat and shell have the same magnitude. d. To calculate the speed of the boat we would need to know the recoil length of the gun. e. A larger mass of shell will increase the recoil force felt by the ship.

3 27. A person jumps from an airplane and reaches terminal speed. a. The momentum of the jumper is constant because there is no external net force. b. The momentum of the person Earth system is not conserved because of air friction. c. When the chute is opened, the force disrupts the conservation of momentum of the person Earth system. d. two of A, B, and C are correct e. all of A, B, and C are correct 28. An arrow slows down from 43 m/s to 28 m/s as it passes through an apple. If the 493-g apple was originally at rest and sped up to 0.44 m/s, the mass of the arrow is a. 5.0 g d. 29 g b. 7.7 g e. 7.7 kg c. 14 g 29. A boy throws a 15-kg ball at 4.7 m/s to a 65-kg girl who is stationary and standing on a skateboard. After catching the ball, the girl is travelling at a. 0 m/s d. 3.2 m/s b m/s e. 4.7 m/s c. 1.1 m/s 30. A goalie standing on a frictionless surface catches a g puck travelling at 95.0 km/h. After catching the puck, the goalie is moving at 8.90 cm/s. The mass of the goalie (including equipment) is a kg d kg b kg e kg c kg 31. A 55-kg person carrying a 5.0-kg ball slides along a horizontal frictionless surface. He tosses the ball perpendicular to his direction of travel relative to himself. a. His path will not change. b. The ball will have a smaller angle from the original path than he will. c. His speed does not change. d. He speeds up. e. He slows down. 32. A 55-kg person carrying a 5.0-kg ball slides along a horizontal frictionless surface. He tosses the ball forward. a. His path will not change. b. The ball will have a smaller angle from the original path than he will. c. His speed does not change. d. He speeds up. e. He will most likely stop moving forward. 33. A moving curling stone, A, collides head on with a stationary stone, B. Both stones are of identical mass. If friction is negligible during this linear elastic collision, a. stone A will slow down b. after the collision, the momentum of stone B will be less than that of stone A c. both stones will come to rest shortly after the collision d. after the collision, the kinetic energy of the stone B will be less than that of stone A e. after the collision, stone A will have a speed of zero 34. If an arrow s mass is doubled and the speed is halved, the momentum is changed by a factor of a d. 2 b. 0.5 e. 4 c A car (of constant mass) doubles its speed while driving up a hill sloped at 45º. The factor by which its momentum changes is a. 0 d. 3

4 b. 1 e. 4 c A car (of constant mass) doubles its kinetic energy while driving down a hill sloped at 45º. The factor by which its momentum changes is a. 1 d. 2.8 b. 1.4 e. 4 c A ball rolling down a hill doubles its speed but reduces its gravitational energy to one-fifth its starting value. The factor by which its momentum changes is a. 0.4 d. 2 b. 1 e. 10 c A ball rolling down a hill doubles its momentum but reduces its gravitational energy to one-third its starting value. The factor by which its kinetic energy changes is a d. 4 b. 1 e. 6 c A 72-kg girl on a skateboard doubles her kinetic energy coasting down a hill. a. Momentum is conserved. b. The increase in kinetic energy is offset by a decrease in momentum. c. The momentum will also double. d. Her momentum does not change. e. none of the above 40. A sabotaged curling stone explodes into three pieces as it travels across the ice. Neglecting the force of friction, a. all three pieces will travel at the same speed b. the magnitudes of the momenta for each piece will be the same c. an external net force had to act on the stone to accelerate the three pieces d. the components perpendicular to the original motion must add up to zero e. momentum is not conserved because of the small explosive charge 41. Two young sisters with a combined mass of 75 kg ride on a cart of mass 30.0 kg travelling at 2.0 m/s. If they jump off together so they land with zero speed relative to the ground, the change in speed of the cart is a. 0 m/s d. 5.0 m/s b. 2.0 m/s e. 7.0 m/s c. 4.0 m/s 42. A force of 4.0 N [S] is applied to a 2.0-kg block sliding west at 3.0 m/s on a smooth surface. The puck will be moving exactly south-west after a. 1.1 s d. 2.8 s b. 1.5 s e. 4.2 s c. 2.1 s 43. A woman of mass M is at rest on a frictionless skateboard of negligible mass. She throws a cement block of mass m with a velocity v relative to the ground. After the throw, her velocity relative to the ground is a. mv d. Mv b. e. c. 44. A two-dimensional collision occurs as shown below.

5 Which vector below most closely represents the new velocity of P? a. A d. D b. B e. E c. C 45. Two objects of equal mass with the speeds indicated by the vectors below, collide and stick together. Which vector below best represents the velocity of the combined objects after the collision? a. A d. D b. B e. E c. C 46. To compare the kinetic energies of two objects, you must know a. their masses d. the forces acting on them b. their velocities e. the work done to stop each of them c. their momenta 47. When you catch a fast-moving baseball, your hand hurts less if you move it in the direction of the ball because a. the ball changes momentum more slowly b. the force applied is smaller c. you decrease the impulse required to stop the ball d. two of A, B, and C

6 e. all of A, B, and C 48. When a baseball bounces on the ground a. momentum is conserved in the Earth ball system b. the impulse is the same as if the baseball landed without bouncing c. it leaves the surface with the same speed that it impacted the surface with d. kinetic energy is imparted to the ground e. the force applied by the surface is smaller than if it didn't bounce 49. Two objects strike a glancing blow. The diagram below shows the momenta of some of the objects are shown before and after the collision. Which vector best represents the momentum of object P after the collision? a. A d. D b. B e. E c. C 50. A gun is mounted on a wooden plank. The plank is stationary and is mounted on frictionless wheels. A heavy wooden block is set in front of the gun, and the gun is fired into the wooden block, which then slows to a stop due to friction between the block and the plank. a. The plank does not move. b. Momentum is not conserved because of the frictional force. c. The speed of the plank is zero immediately after the collision between the bullet and block. d. The plank will have shifted position relative to its starting point. e. Kinetic energy is conserved because the speed of the system is zero before and after the collision. 51. The collision time between a bullet and a block of wood is best measured in a. nanoseconds d. seconds b. microseconds e. hours c. milliseconds

7 52. Without knowing any other information than is given in the diagram below, which deductions could be true? a. The eastbound car was travelling faster. b. The northbound car was lighter. c. Both cars had the same speed. d. two of A, B, and C e. all of A, B, and C Completion Complete each sentence or statement. 53. Linear momentum depends on both the and the velocity of an object. 54. A rotating object possesses momentum. 55. The change in momentum of an object is called the. 56. The proper unit for momentum is and the proper unit for impulse is. 57. If the net force acting on a system of interacting objects is zero, then linear momentum is. 58. Momentum is conserved in a system unless a(n) net force acts on the system. 59. A ball is dropped and bounces back to its original height. The collision between the ball and the ground was. 60. A ball is dropped and bounces back to 90% of its original height. The collision between the ball and the ground was. 61. If you squeeze a rubber ball and it springs back slowly, a collision involving that ball will most likely be. 62. If you squeeze a rubber ball and it springs back quickly, a collision involving that ball will most likely be. Short Answer 63. Why is follow-through so important for maximizing speeds in sporting activities? 64. A 57-g tennis ball travelling at 28 m/s is hit straight back with the same velocity. Determine the average force on the tennis ball if the racket is in contact with the ball for 4.9 ms.

8 65. A blazing spike of a kg volleyball is blocked at the net. It is originally travelling at 18.3 m/s and bounces straight back at 14.9 m/s after being in contact with the blockers arms for a total of 18.2 ms. What average force did the blocker exert on the ball? 66. A raw egg dropped from a height of 1.0 m will break if it lands on a concrete floor, but not if it lands on a thin sponge, even though it experiences the same impulse from each type of drop. Explain why. 67. Why is the follow-through of a badminton racket important? 68. Many vehicles produced today are designed with crumple zones. How does this feature protect the occupants of the car? 69. If a person is standing in a stationary canoe, the total momentum of the person canoe system is zero. If he walks forward and then stops, both the canoe and person are moving. (a) Is momentum conserved? (b) What force is acting on the system? 70. Give two observations that would enable you to conclude that the bounce of a superball is not a completely elastic collision. 71. The captain of a small barge notices the front corner of the boat is on a collision course with a edge of a small pier. What could he ask the passengers to do to help him avoid a collision? 72. As a car coasts down a hill, it gains momentum. State the system that contains the car and where momentum is conserved. Where does the momentum gained by the car come from? 73. During an elastic collision between a superball and the ground, the superball comes to rest for a brief instant. Where is the energy stored? 74. Why are perfectly elastic collisions so unlikely? 75. A 0.25-kg snowball moving at 15 m/s [E] collides and sticks with a 1.9-kg toy truck travelling at 2.8 m/s [W]. Neglecting friction, calculate the velocity of the snowball truck system after the collision. 76. A 25-kg bag of cement thrown at 2.5 m/s [E] is caught by a person sliding 1.8 m/s [E] on a frictionless surface. If the velocity after the catch is 2.0 m/s, calculate the mass of the person. 77. Describe two features of a hockey helmet that help minimize head injury from a slapshot that hits the helmet. 78. A billiard ball collides with an identical stationary billiard ball causing the balls to travel out with speeds of 3.0 m/s and 4.0 m/s at 90º to each other as shown below. Calculate the initial speed of the moving billiard ball. 79. A common novelty sold at many stores consists of five steel balls suspended in a row as shown below. When one is pulled back and released, what happens and why? The collisions between the balls are nearly elastic.

9 80. When you jump off a hay wagon perpendicular to the direction of motion, the hay wagon does not move off in the opposite direction. Why not? 81. Why do you feel the kick back of a gun? 82. Many high-power hand guns need to be held with two hands. Why? 83. At a shooting range for hand guns, you often observe the shooters bend their elbows and allow the gun to move up. Why? 84. How is an inelastic collision different than a completely inelastic collision? 85. Frictional forces are large for colliding vehicles during a car crash. Is conservation of momentum still useful in analyzing these crashes? 86. An arrow undergoing projectile motion passes through an apple while travelling at 45º above the horizontal. Can conservation of linear momentum be used to solve this problem? 87. What advice could be useful to a person who drives a car and habitually cuts in front of large trucks on the highway? Use your knowledge or physics and collisions in your answer. 88. By observing the aerial diagram of an accident scene between two identical cars, which car was travelling more quickly? Problem 89. Two common and identical carts are used to perform an experiment. Cart A is pushed toward the stationary cart B with a velocity of 2.6 m/s. After the collision, cart A bounces back with a speed of 0.8 m/s and cart B moves of with a speed of 3.4 m/s. Why is this not possible? 90. Compare yourself sprinting at 7.0 m/s with a 63-g bullet travelling at 150 m/s. (a) Which has a larger momentum? (b) Which has more energy? (c) Which is more dangerous? Why?

10 91. During a free dance program in figure skating, Victor (m = 71 kg) glides at 2.1 m/s to a stationary Shae-Lynn (52 kg) and hangs on. How far will the pair slide after the collision if coefficient of kinetic friction µ K between their skates and the ice is 0.052? 92. A spring with a force constant of 89 N/m is compressed 8.7 cm and placed between two stationary dynamics carts of mass 1.0 kg and 1.5 kg. If friction is negligible, determine the final speed of the more massive cart when the spring is released. 93. A dog named Pinky throws a pan of lasagna (m = 2.3 kg) at his friend Flowers. The pan hits and sticks to Flowers (m = 6.7 kg), who then slides a total of 2.2 m in 1.4 s. How fast was the lasagna moving before the impact? 94. A 34-g bullet travelling at 120 m/s embeds itself in a wooden block on a smooth surface. The block then slides toward a spring and collides with it. The block compresses the spring (k = 99 N/m) a maximum of 1.2 cm. Calculate the mass of the block of wood. 95. A 0.40-kg cue ball makes a glancing blow to a stationary 0.30-kg billiard ball so that the cue ball deflects with a speed of 1.2 m/s at an angle of 30.0º from its original path. Calculate the original speed of the cue ball if the billiard ball ends up travelling at 1.5 m/s. 96. A small explosive charge is placed in a rubber block resting on a smooth surface. When the charge is detonated, the block breaks into three pieces. A 200-g piece travels at 1.4 m/s, and a 300-g piece travels at 0.90 m/s. The third piece flies off at a speed of 1.8 m/s. If the angle between the first two pieces is 80º, calculate the mass and direction of the third piece. Assume two significant digits for each value. 97. During a game of billiards, the 0.30-kg cue ball, travelling at 2.1 m/s, glances off a stationary 0.28-kg billiard ball so that the billiard ball moves off at 1.4 m/s at an angle of 38º from the cue ball s original path. Find the new speed of the cue ball. 98. A 63-kg student stands on a 34-kg cart that is free to move in any direction. The cart and student are moving together with a velocity of 3.2 m/s [W]. The student then starts to walk so that her velocity is 1.8 m/s [25º W of N] relative to the floor. Calculate the new velocity of the cart. 99. A 38-g bullet is fired with a speed of 180 m/s into a 5.0-kg sandbag pendulum that is free to swing. To what maximum vertical height will the pendulum rise? 100. A bullet with a mass of 45 g is fired into a 8.3-kg block of wood resting on a floor against a spring. This ideal spring (k = 76 N/m) has a maximum compression of 28 cm. What was the initial speed of the bullet? 101. A 1.8-kg block, initially at rest, slides down a frictionless ramp that is angled at 35º to the horizontal. At a point 0.45 m down the slope it collides with and sticks to a stationary block of mass 1.1 kg. The blocks then continue another 0.88 m down the ramp. How long does the whole event take? (For those of you wondering how a block is stationary on a frictionless ramp, it was projected up the ramp from below so it had no speed at the time of impact.) 102. A 1.5-kg cart rolls along a horizontal table at a constant speed of 1.7 m/s. A ball of soft putty is dropped from a stationary hand onto the cart as it passes underneath. If the speed of the cart is reduced to 0.73 m/s, calculate the mass of the ball of putty Two carts of mass 12 kg and 15 kg move toward each other with speeds of 2.3 m/s and 1.5 m/s respectively. If the collision between them is completely inelastic, calculate the velocity of the 15-kg cart after the collision. Essay

11 Different types of rubber vary in elasticity from nearly elastic to almost completely inelastic. Write how an application of each type has affected our society Mass, elasticity, momentum, and energy are very important concepts to consider in the design of a vehicle. Provide support for four different ways designers might consider these concepts in their design Bowling, crokinole, and billiards are common forms of recreation that are based almost entirely on collisions. Choose one activity and describe several ways in which it has affected your life Safety during sporting events becomes increasingly important as people and machines get faster and push the limits of human accomplishment. Choose a sporting event and, referring to concepts covered in this unit, explain how safety equipment minimizes risk of injury and how it has affected the sport. Answer Section MODIFIED TRUE/FALSE 1. F, vector 2. T 3. F, does not accurately represent 4. T 5. F, speed direction and mass are 6. T 7. T 8. F, maintain its speed 9. T 10. F, is conserved 11. T 12. T 13. T 14. F, can 15. F, has reduced MULTIPLE CHOICE 16. E 17. C 18. C 19. E 20. A 21. D 22. E 23. E 24. C 25. B 26. D` A 28. C 29. B 30. B 31. D 32. A 33. E 34. C 35. C 36. B 37. D 38. D 39. E 40. D 41. D 42. B 43. E 44. B 45. D 46. E 47. D 48. A 49. A 50. D 51. C 52. E COMPLETION 53. mass 54. angular 55. impulse 56. kg m/s, N s 57. conserved 58. external 59. elastic 60. inelastic 61. inelastic 62. elastic SHORT ANSWER 63. By continuing the motion of the striking object, you increase the contact time and the impulse transferred to the ball. This extra impulse translates into a faster speed. 64. The average force acting on the ball is N. 65. The average force acting on the ball is 529 N. 66. The sponge slows the egg down more slowly than the concrete. Since the impulse is the same, the larger time from the sponge means a much smaller force is exerted on the egg. 67. The follow-through allows the racket to be in contact with the shuttlecock for a longer period of time, imparting

12 a larger impulse and, therefore, a faster speed to the shuttlecock. 68. The crumple zone is designed to maximize the time (and the distance) over which the force to stop the car is exerted. This reduces the size of the force that acts on the passengers, minimizing the injury. 69. (a) Momentum is not conserved because the total momentum of the person canoe system before and after is not the same. (b) The force that is acting on the system is fluid friction. (Other answers are bouyant force and gravitational force.) The ball does not reach its original height after the bounce. (some loss of energy) - Sound is produced. (sound energy must come from original kinetic energy) 71. By having the passengers walk to the same side of the boat as the pier, the boat will move away from it, helping to avoid a collision. 72. The system is the Earth car system. The Earth is moving toward the car to offset the momentum the gained by the car. (The Earth would have negative momentum.) 73. The energy is stored as elastic potential energy in the deformed shape of the ball. 74. For an elastic collision to take place, all of the initial kinetic energy possessed by the objects must be transferred to the objects after the collision with no loss. No loss of energy is difficult to achieve since some thermal energy is always generated. 75. The final velocity is 0.73 m/s [W]. 76. The mass of the person is 62 kg. 77. The snug fit transmits the force to the whole head instead of just one part. The cushioned padding increases the time to stop and therefore reduces the force necessary to impart the impulse to the puck. 78. The initial speed of the billiard ball was 5.0 m/s. 79. When the ball strikes the first identical ball, all of the momentum will be transferred to it. This will continue along the line until only the last ball swings up into the air. 80. The force of friction (an external force to the system) acts on the wagon. 81. The kick back is caused by the impulse the bullet imparts to the gun. The person shooting the gun acts as the external force to stop this motion and can feel the gun accelerating toward him. 82. Since the bullet is fired at a very high speed, it has a large impulse applied to it. This is applied to the gun in the opposite direction. After the bullet is ejected, the force that one hand is capable of applying is insufficient, so it is suggested that two hands are used. 83. This allows the recoil distance to be larger since their arms can easily bend. Since the recoil takes more time, the force is decreased. The shooters use this technique to minimize the force required to remove the impulse given to the gun after the shot is fired. 84. The completely inelastic collision loses the maximum amount of kinetic energy (usually a hit and stick). An inelastic collision may still be almost elastic (such as the bounce of a superball). 85. Yes. The forces of friction are large, but the crashes occur so quickly that the frictional forces do not play a major role in the actual collision. They just slow vehicles down afterward. 86. Conservation of linear momentum can be used. The gravitational effects are insignificant during the brief interaction between the apple and the arrow. 87. Several possible answers, but most importantly: During a collision, trucks have a much larger mass and are much less likely to suffer large accelerations and the associated damage that you will. 88. The eastbound car had more momentum. Since the cars are identical, the eastbound car must have been moving faster. PROBLEM 89. There is more kinetic energy after the collision than before. This is not possible.

13 ESSAY 90. (a)the student has a much larger momentum. (b)the student also has a larger kinetic energy. (c) The bullet is more dangerous because all of the energy is concentrated on a small part of a target (i.e., a tree, a target, or a person). The work done to stop it is only supplied by a small area, and it passes through many parts before enough work can be done to stop it. The person has the work supplied by a larger surface area and is not as dangerous. 91. The pair coast a total of 1.4 m after the collision. 92. The final speed of the more massive cart is 0.42 m/s. 93. The initial speed of the lasagna is 12 m/s. 94. The mass of the wooden block is 12 kg. 95. The initial speed of the cue ball was 2.0 m/s. 96. The mass of the third piece is 0.23 kg and is moving 141º from the 200-g piece (139º from the 300-g piece.) 97. The new speed of the cue ball is 1.3 m/s. 98. The new velocity of the cart is 8.3 m/s [21º S of W] 99. The sandbag will rise 9.4 cm vertically The impact speed of the bullet was m/s The event takes 0.76 s The mass of the ball of putty is 2.0 kg The final speed of the 15-kg cart is 0.19 m/s Possible topics: Elastic superballs and applications for recreation, sports (lacrosse), childhood experiences. Affect on society is a common (because it is inexpensive) childhood experience. Inelastic bumpers used in manufacturing to stop (without bouncing) boxes to alter direction of travel. To minimize bounce from vehicle collisions. Effect on society is to minimize injury in collisions, and to increase the efficiency of manufacturing to make our society more industrialized Possible ideas - lower mass to reduce power needed to speed the vehicle up - bumper design to minimize bounce - crumple zones to minimize forces on passengers during rapid accelerations - crumple zones to maximize energy absorption - air bags to cushion passengers (impulse) 106. Possible considerations: - personal memories associated with it - learning experiences related to collisions that helped with a specific situation - local establishments known for these forms of entertainment, or ways they think about people who go to them 107. Some possible sports - racing (of anything such as cars, bobsleigh, skiing, boats) - hockey or football - high jump (and a number of other track events) Some of the concepts - impulse (increasing the time of acceleration to minimize force)

14 - momentum (strapping helmet to car seat because of added momentum the neck cannot withstand.)