| A | B |
|---|
| balanced force | forces that act against each other and do not cause a change in motion |
| decrease | to lessen or reduce |
| effort | the use of physical or mechanical energy to do something |
| friction | a force between two surfaces rubbing against each other working against motion |
| gravity | a force that pulls objects toward each other |
| increase | enlarge, add to |
| inertia | the tendency of an object to resist a change in motion |
| lever | a simple machine made of a long bar or board that pivots on a point to lift an object when pushing down on the opposite end |
| mass | the amount of matter in an object or substance |
| momentum | the force or speed of movement |
| potential energy | the energy an object has because of its place or its condition; energy that is stored in an object |
| resistance | a force, such as friction, that prevents or slows down motion |
| screw jack | energy from the sun in the form of heat and light |
| speed | a measure of the distance an object moves in a given amount of time |
| upward force | pull or push that creates upward movement |
| wedge | an object that is thick at one end and thin at the other; an inclined plane |
| wheel and axle | a simple machine made of a shaft inserted through the middle of the circle |
