1. Physics Unit Introduction to Motion
David W. Bombick, Ph.D.
7th Grade Science

2. Definition of Motion
An object is in motion if its distance from another object is changing.
A reference point is a place or object used for comparison to determine if something is in motion.
An object is in motion if it changes position relative to a reference point.

3. Measuring Distance Will use the International System of Units (SI)
The SI unit of length will be the meter.
Prefixes will be used with the word ‘meter’ to describe fractions or multiples of a meter.
For example, a centimeter is one hundredth of a meter; a millimeter is one thousandths of a meter; a kilometer is 1000 times a meter.

4. Calculating Speed
The speed of an object can be calculated by knowing the distance travelled and the amount of time needed to travel this distance.
Therefore, Speed = distance divided by time
SI units are usually in meters and seconds

5. Average Speed
The average speed can be calculated by adding up the total distance travelled and dividing by the total time the object has travelled
An example would be someone who travels for 10 meters over 10 seconds; stops for 10 seconds; and travels 20 meters in 10 seconds has travelled at an average speed of 1 m/sec.