# Chapter 6 Physics

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question
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.
question
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
question
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.
question
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.
question
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 _______.