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