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A Mack truck and a small Volkswagen collide head on. Which of the following statements is true about the collision? |
The force the Volkswagen exerts on the truck is equal to the force the truck exerts on the Volkswagen. |
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A truck rear-ends a car that is initially stationary. The truck weighs ten times more than the car. Which statement is true about the collision? |
The magnitude of the acceleration of the car is ten times greater than the magnitude of the acceleration of the truck. |
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A glass that falls onto a carpeted floor has less chance of breaking than a glass that falls (from the same height) onto a wooden floor. Why? |
The glass that falls onto the carpet takes a longer time to stop. |
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A stationary 100-kg person is initially holding a 50-kg ball while standing on a skateboard. The person throws the ball to the right, and the ball moves (with respect to the ground) with a speed of 12 m/s. The person on the skateboard ____________. |
moves to the left with a speed of 6 m/s |
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Consider two carts, initially at rest. Cart 1 is twice as massive as cart 2. If you push on cart 1 for 3 seconds and then push on cart 2 with the same force for 3 seconds, how do the final momenta of the two carts compare? (Ignore the effect of friction.) |
The momenta of the two carts are equal. |
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Consider two carts, initially at rest. Cart 1 is twice as massive as cart 2. If you push on cart 1 for 3 seconds and then push on cart 2 with the same force for 3 seconds, how do the final speeds of the two carts compare? (Ignore the effect of friction.) |
The speed of cart 2 is twice as great as that of cart 1. |
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A 200-lb person pushes on the back of a 100-lb person. Both people are on skateboards and are initially stationary. After the push, the 200-lb person is moving to the right with a speed of 4 m/s. The 100-lb person is ________. |
moving to the left with a speed of 8 m/s |
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A car is driving down the highway with an initial speed of 30 m/s. It slams into the back of an identical car (same mass), which was initially going only 10 m/s (in the same direction as the faster car). If the collision is perfectly inelastic, the final speed of the two cars is ________. |
20 m/s |
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A slowly moving ship can have a greater momentum than a fast-moving racing car when _______. |
its mass times velocity is greater than that of the car. |
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The quantity that is called impulse can be measured by the _______. |
product of force and time. |
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An impulse can be increased by |
increasing the force or increasing the time interval. |
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A boxer rides with the punch so as to reduce _______. |
force |
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Follow through is important in golf because it results in a greater _______ |
impulse on the ball. |
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Distinguish between force and impulse. |
Impulse is force times a time interval. |
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Which has a greater momentum: a heavy truck at rest or a moving skateboard? |
The moving skateboard. |
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How is the impulse -momentum relationship related to Newton’s second law? |
F=ma=mΔv/Δt, so Ft=Δ(mv) |
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Why is a force that is applied for a short time more effective in karate? |
The average force is increased. |
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Why is it advantageous to roll with the punch in boxing? |
Rolling with the punch increases contact time, which decreases the force. |
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What is the momentum of an 8.6-kg bowling ball rolling at 2.2 m/s ? |
19 kgm/s |
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What is the momentum of a 44-kg carton that slides at 3.4 m/s across an icy surface? |
150 kgm/s |
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What impulse occurs when the force of 14 N acts on the cart for the time 5.4 s ? |
76 kgm/s |
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What is the magnitude of the impulse on an 7.2-kg ball rolling at 2.8 m/s when it bumps into a pillow and stops? |
20 NxS |
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How much impulse stops a 40-kg carton sliding at 4.8 m/s when it meets a rough surface? |
190 NxS |
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What impulse occurs when an average force of 12 N is exerted on a cart for 2.9 s ? |
35 kgm/s |
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Cassy can get more force on the bricks she breaks with a blow of her bare hand when _______. |
her hand is made to bounce from the bricks. |
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When a cannonball is fired from a cannon, the momentum of the recoiling cannon is momentarily _______. |
equal and opposite to the momentum of the fired cannonball. |
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When two vehicles collide, momentum is conserved _______. |
whether the collision is elastic or inelastic. |
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When a big fish swims into an oncoming smaller fish and swallows it, the momentum of the two-fish system _______. |
remains the same. |
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what will happen if the red and green truck with equal mass and equal magnitude of velocity collide? |
The trucks will stick together after the collision and not move. |
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what will happen if you reduce the magnitude of the velocity of the green truck to a magnitude smaller than that of the red truck? |
The trucks will stick together after the collision and move to the left. |
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How much of the balls’ kinetic energy is dissipated? |
None of it |
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When a cue ball strikes an 8 ball head-on in a game of pool, the cue ball _______. |
transfers its momentum to the 8 ball. |
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What does it mean to say that momentum is conserved? |
It means momentum does not change. |
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When a falling firecracker explodes, the momenta of its pieces _______. |
vectorally add up to equal the initial momentum of the firecracker |
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Railroad car A rolls at a certain speed and makes a perfectly elastic collision with car B of the same mass. After the collision, car A is observed to be at rest. How does the speed of car B compare with the initial speed of car A? |
The speed of car B is equal to the initial speed of A. |
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