Physical science Ch 3

A diver who weighs 500 N steps off a diving board 10 m above the water hits the water with kinetic energy of

5000 J.

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 shopping cart moves with a kinetic energy of 40 J. If it moves at twice the speed, its kinetic energy is

160 J.

A music console is pushed a distance of 2 m with a force of 20 N. The work done on the console is

40 J.

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.

It is correct to say that impulse is equal to

change in momentum

If a rhinoceros has momentum, it must also have

kinetic energy.

An object may have potential energy because of its

location

A dog and a mouse run along a road with the same kinetic energy. The faster runner is the

mouse

If you push for an hour against a stationary wall, you do no work

on the wall.

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.

When you are in the way of a fast-moving object and can't get escape, you will suffer asmaller force if the collision time is

long

A 50-kg sack is lifted 2 m in the same time as a 25-kg sack is lifted 4 m. The power expended in raising the 50-kg sack compared to the power used to lift the 25-kg sack is

the same.

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

Two identical freight cars roll without friction towards each other on a level track. One car rolls at 2 m/s and the other car rolls at 1 m/s. After the cars collide, they couple and roll together with a speed of

0.5 m/s.

If you exert 100 J in 50 s and your power output is

2 W.

A 1000-kg car moving at 10 m/s that brakes to a stop in 5 s has an average braking forceof

2000 N

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

3 m/s

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 lunch is

5/6 m/s.

A freight train rolls along a track with considerable momentum. If it rolls at the samespeed but has twice as much mass, its momentum is

doubled

When a cannon fires a cannonball at a given speed, the smaller recoil speed of the cannonis due to different

masses

From the same height you simultaneously drop a lightweight tennis ball and aheavyweight bowling ball. When they hit the floor they have the same

speed