| A | B |
|---|
| force | cause that makes something move or stop moving |
| gravity | the force that pulls objects to Earth |
| friction | the force of one object rubbing against another object |
| inertia | objects at rest will stay at rest; objects in motion will stay in motion |
| Newton's First Law of Motion | objects at rest will stay at rest; objects in motion will stay in motion at the same speed and direction unless acted upon by an outside force |
| work | when a force is used to move something |
| lever | a bar used for raising or moving an object |
| wheel and axle | a bar that is attached to a wheel that turns when the wheel is turned |
| pulley | a machine with one or more wheels connected by a rope |
| inclined plane | a flat surface with one end raised higher that the other |
| screw | an inclined plane wrapped around a center that lifts things and holds things together |
| wedge | an inclined plane that is wider at one end and tapers to a point; used to cut things |
