Speed and Velocity

Speed: how fast an object is moving.

The Average Speed of an object is defined as the distance traveled along its path divided by the time it takes to travel this distance:

A person walked 70 m east and then 30 m west.

The total distance traveled was 70 m + 30 m = 100 m.

Suppose this walk took 70 s to complete.

The average speed was : distance /time = 100 m / 70 s
= 1.4 m/s.

Velocity is used to signify both magnitude of how fast an object is moving and the direction in which it is moving.

Velocity is a vector.

Average Velocity is defined in terms of displacement.

A person walked 70 m east and then 30 m west. The displacement was 40 m.

Suppose this walk took 70 s to complete.

The average velocity was : displacement/time = 40 m/ 70 s = 0.57 m/s .

Instantaneous Speed - speed at any given instant in time.

Average Speed - average of all instantaneous speeds; found simply by a distance/time ratio.

Constant Speed & Changing Speed