| A | B |
|---|
| work | the result of a force moving an object |
| energy | the ability to do work |
| kinetic energy | energy of motion |
| potential energy | stored energy |
| mechanical energy | the energy an object gets from its motion |
| chemical energy | energy that results from chemical changes |
| gravity | force that pulls objects toward the center of the earth |
| inertia | tendency of a moving object to stay in motion or a resting object to stay still |
| efficiency | amount of work a machine does compared to the amount of energy put into using the machine |
| friction | resulsts when two objects rub against each other |
| simple machine | usually made of one or two parts |
| compound machine | made of two or more simple machines |
| complex machine | made of many simple and compound machines |
