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Chapter 9 The cart’s change of momentum is 1. –30 kg m/s. 2. –20 kg m/s. 3. –10 kg m/s. 4. 10 kg m/s. 5. 30 kg m/s. The cart’s change of momentum is 1. –30 kg m/s. 2. –20 kg m/s. 3. –10 kg m/s. 4. 10 kg m/s. 5. 30 kg m/s. A 10 g rubber ball and a 10 g clay ball are thrown at a wall with equal speeds. The rubber ball bounces, the clay ball sticks. Which ball exerts a larger impulse on the wall? 1. The clay ball exerts a larger impulse because it sticks. 2. The rubber ball exerts a larger impulse because it bounces. 3. They exert equal impulses because they have equal momenta. 4. Neither exerts an impulse on the wall because the wall doesn’t move. A 10 g rubber ball and a 10 g clay ball are thrown at a wall with equal speeds. The rubber ball bounces, the clay ball sticks. Which ball exerts a larger impulse on the wall? 1. The clay ball exerts a larger impulse because it sticks. 2. The rubber ball exerts a larger impulse because it bounces. 3. They exert equal impulses because they have equal momenta. 4. Neither exerts an impulse on the wall because the wall doesn’t move. Objects A and C are made of different materials, with different “springiness,” but they have the same mass and are initially at rest. When ball B collides with object A, the ball ends up at rest. When ball B is thrown with the same speed and collides with object C, the ball rebounds to the left. Compare the velocities of A and C after the collisions. Is vA greater than, equal to, or less than vC? 1. vA > vC 2. vA = vC 3. vA < vC Objects A and C are made of different materials, with different “springiness,” but they have the same mass and are initially at rest. When ball B collides with object A, the ball ends up at rest. When ball B is thrown with the same speed and collides with object C, the ball rebounds to the left. Compare the velocities of A and C after the collisions. Is vA greater than, equal to, or less than vC? 1. vA > vC 2. vA = vC 3. vA < vC An explosion in a rigid pipe shoots out three pieces. A 6 g piece comes out the right end. A 4 g piece comes out the left end with twice the speed of the 6 g piece. From which end does the third piece emerge? 1. Left end 2. Right end An explosion in a rigid pipe shoots out three pieces. A 6 g piece comes out the right end. A 4 g piece comes out the left end with twice the speed of the 6 g piece. From which end does the third piece emerge? 1. Left end 2. Right end The two particles are both moving to the right. Particle 1 catches up with particle 2 and collides with it. The particles stick together and continue on with velocity vf. Which of these statements is true? 1. 2. 3. 4. 5. vf is greater than v1. vf = v1 . vf is less than v2. vf = v2 . vf is greater than v2, but less than v1. The two particles are both moving to the right. Particle 1 catches up with particle 2 and collides with it. The particles stick together and continue on with velocity vf. Which of these statements is true? 1. 2. 3. 4. 5. vf is greater than v1. vf = v1 . vf is less than v2. vf = v2 . vf is greater than v2, but less than v1. A dry ice (solid carbon dioxide) puck revolves in a circle on the end of a lightweight rigid rod that turns on frictionless bearings. A cushion of CO2 gas allows the puck to glide across the surface without friction. As the puck sublimates (changes from a solid to a gas), its speed 1. increases. 2. decreases. 3. stays the same. A dry ice (solid carbon dioxide) puck revolves in a circle on the end of a lightweight rigid rod that turns on frictionless bearings. A cushion of CO2 gas allows the puck to glide across the surface without friction. As the puck sublimates (changes from a solid to a gas), its speed 1. increases. 2. decreases. 3. stays the same. Chapter 9 Reading Quiz Impulse is 1. a force that is applied at a random time. 2. a force that is applied very suddenly. 3. the area under the force curve in a force-versus-time graph. 4. the time interval that a force lasts. Impulse is 1. a force that is applied at a random time. 2. a force that is applied very suddenly. 3. the area under the force curve in a force-versus-time graph. 4. the time interval that a force lasts. The total momentum of a system is conserved 1. 2. 3. 4. always. if the system is isolated. if the forces are conservative. never; it’s just an approximation. The total momentum of a system is conserved 1. 2. 3. 4. always. if the system is isolated. if the forces are conservative. never; it’s just an approximation. In an inelastic collision, 1. 2. 3. 4. 5. impulse is conserved. momentum is conserved. force is conserved. energy is conserved. elasticity is conserved. In an inelastic collision, 1. 2. 3. 4. 5. impulse is conserved. momentum is conserved. force is conserved. energy is conserved. elasticity is conserved.