1. Gravity

a force of attraction between objects that is due to their masses...what makes objects fall to the ground when you throw them.

2. Weight

a measure of the gravitational force on an object.

3. Mass

measure of the amount of matter in an object.

4. Acceleration

the rate at which velocity (speed) changes over time...when something goes faster.

5. Terminal velocity

When an object stops accelerating (getting faster) and falls at a constant velocity.

6. Free fall

when gravity is pulling an object down but there are not other forces acting on it....can only happen where there is no air, such as in a vacuum.

7. Projectile motion

the curved path an object follows when it is thrown or propelled near the surface of the Earth.

8. Horizontal movement

movement parallel to the ground.

9. Vertical movement

movement perpendicular to the ground.

10. Inertia

the tendency of all objects to resist any change in motion.

11. Newton's First Law

An object remains at rest, or at a constant speed, unless acted on by an unbalanced force.

12. Newton's Second Law

The acceleration of an object depends on the mass of the object and the amount of force applied.

13. Newton's Third Law

Whenever one object exerts a force on a second object, the second object exerts an equal and opposite force on the first.