| A | B |
|---|
| First Law of Motion | Objects at rest will stay at rest and objects in motion will stay in motion unless acted upon by another force. |
| friction | The rubbing of one thing against another causing heat energy. The force of friction resists motion between the two surfaces. |
| inertia | The tendency of an object to remain at rest if at rest or if in motion to remain in motion in the same direction. Example: You tend to keep going forward if the bus driver slams on the brakes. |
| lubricants | Liquids or fine powders used to reduce the friction between two surfaces. Examples: oil and silicone. . |
| newton | A unit used to measure force. This unit is the force needed to accelerate a one-kilogram object by one meter per second every second. |
| Sir Isaac Newton | A scientist who discovered (about 1665) that the force keeping Earth in its orbit around the sun is gravity. |
| Second Law of Motion | An object's acceleration depends on the mass of the object and the strength of the force acting upon it. |
| Third Law of Motion | For every action there is an equal and opposite reaction. |
