Test 2: Review B Flashcards
It is correct to say that impulse is equal to
A) the change in momentum.
B) momentum.
C) the force multiplied by the distance the force acts.
D) velocity multiplied by time
A) the change in momentum.
A rifle recoils while firing a bullet. The speed of the rifle’s recoil is small because the
A) momentum of the rifle is smaller.
B) force against the rifle is smaller than against the bullet.
C) rifle has much more mass than the bullet.
D) momentum is mainly concentrated in the bullet.
C) rifle has much more mass than the bullet.
In order to catch a ball, a baseball player extends the hand forward before impact with the ball and then lets it ride backward in the direction of the ball’s motion. Doing this reduces the force of impact on the player’s hand principally because the
A) time of impact is decreased.
B) force of impact is reduced.
C) relative velocity is less.
D) time of impact is increased.
E) none of these
D) time of impact is increased.
A 4 kg ball has a momentum of 12 kg m/s. What is the ball’s speed?
A) 48 m/s
B) 3 m/s
C) 12 m/s
D) 4 m/s
B) 3 m/s
Recoil is noticeable if we throw a heavy ball while standing on roller skates. If instead we go through the motions of throwing the ball but hold onto it, our net recoil will be
A) small, but noticeable.
B) the same as before.
C) zero.
C) zero.
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
A) greater.
B) the same.
C) smaller.
A) greater.
A karate expert executes a swift blow and breaks a cement block with her bare hand. The magnitude of the force experienced by her hand is
A) zero.
B) less than the force applied to the cement block.
C) more than the force applied to the block.
D) identical to the force applied to the block.
E) impossible to predict without additional information.
D) identical to the force applied to the block.
Two billiard balls having the same mass and speed roll toward each other. What is their combined momentum after they meet?
A) 0
B) twice the sum of their original momentums
C) half the sum of their original momentums.
D) impossible to determine without additional information
A) 0
A 1000-kg car moving at 10 m/s brakes to a stop in 5 s. The average braking force is
A) 4000 N.
B) 2000 N.
C) 1000 N.
D) 5000 N.
E) 3000 N.
B) 2000 N.
A 5-kg fish swimming at a speed of 1 m/s swallows an absent-minded 1-kg fish at rest. The speed of the larger fish after this lunch is
A) 2/5 m/s.
B) 6/5 m/s.
C) 5/6 m/s.
D) 1/2 m/s.
E) 1 m/s.
C) 5/6 m/s.
You’re driving down the highway and a bug spatters into your windshield. Which undergoes the greater change in momentum during the time of contact?
A) your car
B) the bug
C) both the same
C) both the same
If a monkey floating in outer space throws his hat away, the hat and the monkey will both
A) move away from each other at the same speed.
B) move a short distance and then go faster.
C) move a short distance and then slow down.
D) move away from each other, but at different speeds.
E) come to a stop after a few minutes.
D) move away from each other, but at different speeds.
If you push an object twice as far while applying the same force, you do
A) half as much work.
B) the same amount of work.
C) four times as much work.
D) twice as much work.
D) twice as much work.
A job is done slowly, while an identical job is done quickly. Both jobs require the same amount of work, but different amounts of
A) energy.
B) effort.
C) power.
D) none of these
C) power.
If an object is raised twice as high, its potential energy will be
A) four times as much.
B) half as much
C) twice as much.
D) impossible to determine unless the time is given.
C) twice as much.
An object that has kinetic energy must be
A) falling.
B) at an elevated position.
C) at rest.
D) moving.
E) none of these
D) moving.
A clerk can lift containers a vertical distance of 1 meter or can roll them up a 2 meter-long ramp to the same elevation. With the ramp, the applied force required is about
A) the same.
B) half as much.
C) four times as much.
D) twice as much.
B) half as much.
The ball rolling down an incline has its maximum potential energy at
A) halfway down.
B) a quarter of the way down.
C) the top.
D) the bottom.
C) the top.
Using 1000 J of work, a toy elevator is raised from the ground floor to the second floor in 20 seconds. The power needed to do this job was
A) 50 W.
B) 100 W.
C) 20,000 W.
D) 20 W.
E) 1000 W.
A) 50 W.
A TV set is pushed 2 m with a force of 20 N. How much work is done on the set?
A) 20 J
B) 2 J
C) 800 J
D) 10 J
E) 40 J
E) 40 J
