Motion, Speed and Velocity

Motion

Motion occurs when two forces that are opposing each other become unbalanced.

Frame of Reference

Your description of motion always depends on some frame of reference.

If you describe something that is moving your reference is something that is not moving.

Speed

When motion happens, the matter involved has speed.

Speed can be either Instantaneous or Average.

Instantaneous Speed

Instantaneous speed is the speed at one instant in time.

Average Speed

Average speed is the total distance an object moves divided by the total time it takes to move that distance.

Unit for Speed

The units for speed can vary but are always a unit of distance over a unit of time.

Examples:

Miles per Hour (m/h or mph)

Meters per Second (m/s)

WE WILL USE METRIC UNITS!

Calculations

This is the speed formula: Speed = Distance divided by Time

Use D = ST

Velocity

Velocity is the exact same thing as speed, but it also includes the direction an object is going.

Velocity Example

An example would be an airplane flying at 320 meters per second due east.

Speed is “320 meters per second.”

Velocity is “320 meters per second due east.”

Change in Velocity

A change in velocity is:

a change in speed, or

a change in direction, or

a change in speed and direction.

Questions

1. What is a frame of reference?

2. What is instantaneous speed?

3. What is average speed?

4. What is velocity?

5. What is a change in velocity?