1. Unit 2- Force and Motion Vocabulary- Part I

2. Frame of Reference  A system of objects that are not moving with respect to each other

3. Relative Motion  Movement in relation to a frame of reference

4. Distance  Length between two points

5. Displacement  The position with respect to the origin; the length and direction from the starting point to the ending point.

6. Speed  Ratio of the distance traveled to the time the object moves

7. Average Speed  The total distance traveled divided by the total time traveled

8. Instantaneous Speed  The rate at which an object is moving at a given moment in time.

9. Velocity  A description of motion involving both speed and direction.

10. Acceleration  The change in velocity. It can occur when speed changes, when direction changes or when both speed and direction changes.

11. Free Fall  The movement of an object toward Earth because of gravity.

12. Constant Acceleration  A steady change in velocity