1-5 work and energy (knowledge)

When a car is braked to a stop, its kinetic energy is transformed to

Heat

A child is sledding down a gently-sloped hill and slowing down. Which one of the following statements is true of the child?

Its kinetic energy is decreasing

An object is moving horizontally and increasing its speed. Which one of the following statements is true of the object?

Its potential energy is constant

An object is moving uphill and slowing down. Which one of the following statements is true of the object?

Its potential energy is increasing

A ball rolling on the ground.

KE

A car is traveling 45 mph.

KE

equation for KE

KE=1/2(m)(v^2)

A car is resting at the top of a hill.

PE

A rock is on a ledge 5 meters high.

PE

units for KE

joules(J)

units for mass

kilograms/ grams (kg/g)

An object may have potential energy because of its

location

units for velocity

m/s (v)

An object that has kinetic energy must be

moving

What task requires the most work; lifting a 50-kg sack 2 meters or lifting a 25-kg sack 4 meters?

same

After rolling halfway down an incline a marble's kinetic energy is

the same as its potential energy

If you push an object twice as far while applying the same force, you do

twice as much work