Potential and Kinetic Energy

What is energy?!

• Capacity to do work• Measured in joules (J)

Potential Energy

• Energy stored in an object – Dependent upon: • Position – top of a hill vs bottom of a hill• Shape - stretched rubber band, compressed spring• Condition – old battery vs new battery

• Commonly used as fuel to “run” things• Ex: batteries, gasoline/fuel, food, object at the

top of a hill, acorn hanging on a tree, etc.

Types of PE

• Chemical (food, gasoline, other fuels)• Nuclear (fission, fusion)• Gravitational (one object above another)• Stored mechanical (elastic PE)

Kinetic Energy

• Energy of an object due to its motion.– Dependent upon:• Mass – bowling ball vs a marble• Speed – car traveling at 75mph vs 25 mph

• Ex: person running, Frisbee flying, baseball moving through air, car traveling down road

Forms of KE

• Sound – travels in waves, must have something to travel through

• Radiant – travels in waves, doesn’t have to have a medium

• Electrical – when e- move (lightning, electricity)

Law of Conservation of Energy

Energy can be neither created, not destroyed BUT can change from one form to another.

(Amount of energy in a system remains constant!)

KE can change to PE, or vice versa!Energy can be transferred as work and heat

thermodynamics