Energy Review

In physics, work is defined as

• force times time

• force divided by time

• force times distance

• force divided by distance

• distance divided by time

How many joules of work are done on an object when a force of 10 N pushes it 5 m?

• 50 J

• 10 J

• 5 J

• 2 J

• 1 J

How much power is required to do 100 J of work on an object in 2 seconds?

• 200 W

• 100 W

• 50 W

• 2 W

• 0 W

Potential energy is the energy an object has because of its

• speed

• location

• size

• temperature

• density

Suppose a moving car has 2000 J of kinetic energy. If the car's speed doubles, how much kinetic energy would it then have?

• 8000 J

• 6000 J

• 4000 J

• 2000 J

• 1000 J

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

• 140 J

• 70 J

• 50 J

• 35 J

• 0 J

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

• one quarter as much

• half as much

• twice as much

• four times as much

• the same amount

It takes 40 J to push a large box 4 m across a floor. Assuming the push is in the same direction as the move, what is the magnitude of the force on the box?

• 4 N

• 10 N

• 40 N

• 160 N

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, its kinetic energy is

• less than 100 J

• more than 100 J

• 100 J

• not enough information given

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

• the 30 km/h car

• the 60 km/h car

• both have the same kinetic energy