Physical Exam 2

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?

0 kg 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?

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

2000 N

A 4-kg ball has a momentum of 12 kg∙m/s. What is the ball's speed?

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?

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

80 J

The impulse-momentum relationship is a direct result of

Newton's second law

The conservation of momentum is closely related toǒ

Newton's third law

Whereas impulse involves the time that a force acts, work involves the

a distance that a force acts

Which of the following has the largest momentum relative to Earth?

a pickup truck speeding along a highway

When bullets are fired from an airplane in the forward direction of motion, the momentum of the airplane

decrease

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

doubled

The force that accelerates a rocket in outer space is exerted on the rocket by the

exhaust gases

Padded dashboards in cars are safer in an accident than non-padded ones because an occupant hitting the dash has

increased time of contact and decreased contact force.

If a charging rhinoceros has momentum, it must also have

kinetic energy

An object may have potential energy because of its

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

long

A heavy truck and a small truck roll down a hill. Neglecting friction, at the bottom of the hill the heavy truck has greater

momentum

An object in motion will continue in motion with

momentum

A car traveling along the highway needs a certain amount of braking force to stop. More braking force is required when the car has

more mass , more momentum , less stopping distance

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

speed

It is correct to say that impulse is equal to

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

time of catch is increased

The distinction between impulse and force involves the

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

twice as much