Physics Chp. 8

An arrow in a bow has 70 J of potential energy. Assuming no loss of energy to heat, how much kinetic energy will it have after it had been shot?

70 J

Which has greater kinetic energy, a car traveling at 30 km/h or a half-as-massive car traveling at 60 km/h?

The 60 km/h car

If you lift one load up two stories, how much work do you do compared to lifting one load up only one story?

Twice as much

If you lift two loads up one story, how much work do you do compared to lifting one load up one story?

Twice as much

The amount of potential energy possessed by an object is equal to

one half the product of its mass times it's speed squared

A job is done slowly, and an identical job is done quickly. Both jobs require the same amount or work but different amounts of

power

How much farther will a car traveling at 100 km/s skid than the same car traveling at 50 km/s?

Four times as fast

If Nellie Newton pushes an object with twice the force for twice the distance, she does

four times the work

When a cars speed triples, it's kinetic energy

increases by nine times

The unit of work is the

joule

The unit of power is the

watt

Power is defined as the

work done on an object divided by the time taken to do the work

A woman can lift barrels a vertical distance of 1 meter or can roll them up a 2 meter long ramp to the same elevation. If she uses the ramp, the applied force required is

1/2 as much

A person on a roof throws one ball downward and an identical ball upward at the same speed. The ball thrown downward hits the ground with 140 J of kinetic energy. Ignoring air friction, with how much kinetic energy does the second ball hit the ground?

140 J

Energy is changed from one form to another with no net loss or gain

Always true

Which requires more work: lifting a 70 kg sack vertically 2 meters or lifting a 35 kg sack vertically 4 meters?

Both require the same amount of work

As a pendulum swings back and forth

all of the above (at the end points of its swing it's energy is all potential, at the lowest part of its swing it's energy is all kinetic, kinetic energy is transformed into potential energy, potential energy is transformed into kinetic energy)

Rockets are launched from an airplane in the forward direction of motion. The kinetic energy of the airplane will be

decreased

An object at rest may have

energy

In, physics work is defined as

force times distance

A ball is thrown into the air with 100 J of kinetic energy, which is transformed to gravitational potential energy at the top of its trajectory. When it returns to its original level after encountering air resistance, it's kinetic energy is

less than 100 J

Potential energy is the energy an object has because of its

location

The ratio of output force to input force of a simple machine is called the

mechanical advantage

An object that has kinetic energy must have

momentum

If an object has kinetic energy, then it also must have

momentum

If the velocity of a moving object doubles, then what else doubles?

momentum

An object that has kinetic energy must be

moving

A heavy object and a light object are released from rest at the same height and time in a vacuum. As they fall, they have equal

none of the above (energies, weights, momenta)

All simple machines ideally work on the principal that

work input equals work output