PSSI: Chapter 3 Reading Check – Flashcards
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Padded dashboards in cars are safer in an accident than nonpadded ones because an occupant hitting the dash has
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Increased time of impact and decreased impact force
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An object that has potential energy may have this energy because of its
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Location
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Which requires the most amount of work on the brakes of a car?
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Slowing down from 100 km/h to 70 km/h
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A cannonball shot from a cannon with a long barrel will have a greater muzzle velocity because the cannonball receives a greater
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Impulse
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The force on an apple hitting the ground depends upon - The time of impact with the ground - Whether or not the apple bounces - The speed of the apple just before it hits - All of these
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All of these
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If you push for an hour against a stationary wall, you do no work
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On the wall
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A heavy truck and a small car rolling down a hill at the same speed are forced to stop in the same amount of time. Compared to the force that stops the car, the force needed to stop the truck is
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Greater
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The force that accelerates a rocket in outer space is exerted on the rocket by the
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Exhaust gases
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Compared to a recoiling rifle, the bullet fired has a greater
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Kinetic energy
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A golf ball is thrown at and bounces backward from a massive bowling ball that is initially at rest. After the collision, compared to the golf ball, the bowling ball has more
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Momentum, but less kinetic energy
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A freight train rolls along a track with considerable momentum. If it rolls at the same speed but has twice as much mass, its momentum is
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Doubled
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Suppose a gun were made of a strong but very light material. Suppose also that the pellet is more massive than the gun itself. For such a weapon
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The target would be safer than the shooter
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If you do work on an object in half the time, your power output is
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Twice the usual power output
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In bungee jumping, the change in a jumper's kinetic energy equals the average force of the bungee cord multiplied by the stretching
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Distance
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A karate expert executes a swift blow and severs a cement block with her bare hand. The magnitude is the same for the - Impulse of both the block and the expert's hand - Force on both the block and the expert's hand - None of these - All of these - Time of impact on both the block and the expert's hand
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All of these
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Momentum is transferred to the ground when an apple falls on it. The momentum absorbed by the ground is
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Greater than that of the apple only if the apple bounces
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Two identical arrows, one with twice the kinetic energy of the other, are fired into a hay bale. The faster arrow will penetrate
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Twice as far as the slower arrow
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A car that travels twice as fast as another when braking to a stop will skid
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Four times as far
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Strictly speaking, if any electrical device in your car is turned on (such as an air conditioner, headlights, or even a radio), more gasoline is burned by the engine. This statement is
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Always true
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Two identical arrows, one with twice the speed of the other, are fired into a hay bale. The faster arrow will penetrate
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Four times as far as the slower arrow
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The conservation of momentum is most closely related to
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Newton's third law
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An object at rest may have
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Energy
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An open freight car rolls friction-free along a horizontal track in a pouring rain that falls vertically. As water accumulates in the car, its speed
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Decreases
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When a car is braked to a stop, its kinetic energy is transformed to
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Heat
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If you push an object twice as far while applying the same force, you do
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Twice as much work
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A karate expert executes a swift blow and severs a cement block with her bare hand. The magnitude is the same for the - All of these - Time of impact on both the block and the expert's hand - Force on both the block and the expert's hand - None of these - Impulse on both the block and the expert's hand
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All of these
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Whereas impulse involves the time that a force acts, work involves the
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Distance that a force acts
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A heavy and a light object released from the same height in a vacuum have equal - All of these - Energies - None of these - Momenta - Weights
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None of these
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A moving object has - All of these - Velocity - Speed - Energy - Momentum
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All of these
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Bullets are fired from an airplane in the forward direction of motion. The momentum of the airplane will be
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Decreased
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An object is raised above the ground gaining a certain amount of potential energy. If the same object is raised twice as high, it gains
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Twice as much potential energy
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What does an object have when moving that it doesn't have when at rest?
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Momentum
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Two billiard balls having the same mass roll toward each other, each moving at the same speed. What is the combined momentum of the two balls?
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0 kg/m/s
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A cannon recoils from firing a cannonball. The speed of the cannon's recoil is small because the
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Cannon has more mass than the ball
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A bullet is fired from a gun. The speed of the bullet will be about the same as the speed of the recoiling gun
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If the mass of the bullet equals the mass of the gun
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If an object has kinetic energy, then it also must have
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Momentum
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Compared with the force that brings a small car to a stop, the force required to bring a heavy truck traveling at the same speed to a stop
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Depends on the time involved
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The difference between impulse and impact force involves the
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Time the force acts
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A feather and a coin dropped in a vacuum fall with equal
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Accelerations
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A moving object on which no forces are acting will continue to move with constant
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Momentum
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The impulse-momentum relationship is a direct result of
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Newton's second law
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You're driving down the highway and a bug spatters into your windshield. Which undergoes the greater change in momentum?
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Both the same
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A golf ball is thrown at and bounces backward from a massive bowling ball that is initially at rest. After the collision, compared to the golf ball, the bowling ball has more
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Momentum, but less kinetic energy
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A heavy pile driver starting from rest falls on a pile with a force that depends on the
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All of these
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A karate expert executes a swift blow and severs a cement block with her bare hand. The magnitude is the same for the - All of these - None of these - Force on both the block and the expert's hand - Impulse on both the block and the expert's hand - Time of impact on both the block and the expert's hand
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All of these
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An object that has kinetic energy must be
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Moving
