Chapter 7

A wrecking ball with a mass of 2000 kg has a potential energy of 74000 J. At what height is the wrecking ball above the ground?

34

The work done in pushing a TV set a distance of 2 m with an average force of 20 N is..

40 J

A car with a mass of 1430 kg is moving with a 21500 J of kinetic energy. What is the velocity of the car?

5.48 m/s

A 2-kg bowling ball is held 4 m above the ground. Relative to the ground it's potential energy is..

80 J

A ball rolling down an incline has its maximum potential energy at..

The bottom

A crate of grapes lifted 10 meters gains 200 J of potential energy. If the same crate is instead lifted 20 meters, it's gain in potential energy is..

Twice as much

A 1000-kg car and a 2000-kg car are lifted to the same height. Raising the more massive car requires..

Twice as much work

Impulse involves the time a force acts, whereas work involves the..

Distance that a force acts

What is the definition of the Law of Conservation of Energy?

Energy cannot be created or destroyed. It can be transformed from one form to another, but the total amount of energy never changes

Machines are used to multiple..

Force

Two identical golf carts move at different speeds. The faster car has twice the speed and therefore has..

Four times the kinetic energy

Name 5 different types of energy.

Gravitational, kinetic, thermal, radiant and nuclear

What are the six simple machines?

Lever, pulley, screw, wedge, wheel and axle, and inclined plane

An object has gravitational potential energy due to its..

Location

If a bowling ball and a golf ball both move in the same direction with the same amount of kinetic energy, the speed of the golf ball must be..

More than the bowling ball

An object that has kinetic energy must be..

Moving

A ball is thrown straight up into the air with 500 J of KE. At what point is KE the greatest? At what point are PE and KE equal to each other?

PE is the greates when the ball reaches the highest point. KE is greatest right before the ball hits the ground.

Both a 50-kg sack is lifted 2 meters from the ground and a 25-kg sack is lifted 4 meters in the same time. The power expended in raising the 50-kg sack is..

The same

About 40 J is required to push a crate 4 m across a floor. If the push is in the same direction as the motion of the crate, the force on the crate is about..

10 N

A machine puts out 100 watts of power for every 1000 watts put into it. The efficiency of the machine is..

10%

A simple machine is used to..

Change the direction of the force acting on the object and multiply the force acting on an object