phy sc test 2 homework

Two billiard balls having the same mass roll toward each other at the same speed. What is the net momentum of the two-ball system? Select one: a. 0 kg∙m/s b. 10 kg∙m/s c. not enough information

0 kg x m/s

A ball is moving at 4 m/s and has a momentum of 48 kg∙m/s. What is the ball's mass? Select one: a. 4 kg b. 12 kg c. 48 kg d. 192 kg

12 kg

A 1000-kg car moving at 10 m/s that brakes to a stop in 5 s has an average braking force of Select one: a. 1000 N. b. 2000 N. c. 3000 N. d. 4000 N. e. 5000 N.

2000 N

A 4-kg ball has a momentum of 12 kg∙m/s. What is the ball's speed? Select one: a. 3 m/s b. 4 m/s c. 12 m/s d. 48 m/s

3 m/s

A 5000-kg freight car crashes into a 10,000-kg freight car at rest. They couple upon collision and move with a speed of 2 m/s. What was the initial speed of the 5000-kg freight car? Select one: a. 4 m/s b. 5 m/s c. 6 m/s d. 6 m/s

6 m/s

A 2-kg mass weighs 20 N and is held 4 m above the ground. Its potential energy relative to the ground is Select one: a. 8 J. b. 20 J. c. 60 J. d. 80 J.

80 J

Which of the following has the largest momentum relative to Earth? Select one: a. a tightrope walker crossing Niagara Falls b. a pickup truck speeding along a highway c. a Mack truck parked in a lot d. a dog running down the street

a pickup truck speeding along a highway

A car traveling along the highway needs a certain amount of braking force to stop. More braking force is required when the car has Select one: a. more mass. b. more momentum. c. less stopping distance. d. all of the above

all the above

Padded dashboards in cars are safer in an accident than non-padded ones because an occupant hitting the dash has Select one: a. increased time of contact. b. decreased contact force. c. both d. neither of these

both

When bullets are fired from an airplane in the forward direction of motion, the momentum of the airplane Select one: a. decreases. b. is unchanged. c. increases.

decreases

Whereas impulse involves the time that a force acts, work involves the Select one: a. distance that a force acts. b. time and distance that a force acts. c. acceleration that a force produces

distance that a force acts

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 Select one: a. zero b. doubled c. quadrupled d. unchanged

doubled

The force that accelerates a rocket in outer space is exerted on the rocket by the Select one: a. rocket's engine. b. rocket's wings. c. atmospheric pressure. d. exhaust gases.

exhaust gases

If a charging rhinoceros has momentum, it must also have Select one: a. potential energy. b. kinetic energy.

kinetic

An object may have potential energy because of its Select one: a. speed. b. momentum. c. acceleration. d. location.

location

When you are in the way of a fast-moving object and can't get escape, you will suffer a smaller force if the collision time is Select one: a. long. b. short. c. the same way either way.

longgggggg

A heavy truck and a small truck roll down a hill. Neglecting friction, at the bottom of the hill the heavy truck has greater Select one: a. speed b. acceleration c. momentum d. all of the above

momentum

An object in motion will continue in motion with Select one: a. acceleration b. impulse c. momentum

momentum

The impulse-momentum relationship is a direct result of Select one: a. Newton's first law b. Newton's second law c. Newton's third law

newtons 2nd law

The conservation of momentum is closely related to Select one: a. Newton's first law. b. Newton's second law. c. Newton's third law.

newtons 3rd law

From the same height you simultaneously drop a lightweight tennis ball and a heavyweight bowling ball. When they hit the floor they have the same Select one: a. speed b. force c. momentum

speed

It is correct to say that impulse is equal to Select one: a. momentum. b. the change in momentum. c. the force multiplied by the distance the force acts. d. all of the above

the change in momentum

In order to catch a fast-moving softball with your bare hand, you extend your hand forward just before the catch and then let the ball ride backward with your hand. Doing this reduces the catching force because the Select one: a. relative velocity is less. b. relative velocity is more. c. time of catch is increased. d. time of the catch is decreased.

time of catch is increased

The distinction between impulse and force involves the Select one: a. distance the force acts. b. time the force acts. c. difference between acceleration and velocity. d. mass and its effect on resisting a change in momentum.

time the force acts

An object lifted 10 m gains a certain amount of potential energy. If it is lifted 20 m, its gain in potential energy is Select one: a. less. b. the same. c. twice as much. d. four times as much. e. more than four times as much.

twice as much