Science Motion
Reference Points
A reference point is a place or object used for comparison to determine if something is moving. An object is in motion if it changes position relative to a reference point. Reference points should be stationary. Example: a chair, a tree...
Describing and Measuring Motion
An object is in motion if its distance from another object is changing. If you are sitting in a chair you are not moving relative to the chair since your distance from the chair is not changing.
Suppose you are riding in a car. Describe your motion relative to the car and road. Explain why.
Car: Stationary / not moving relative to the road Road: Moving at the same speed as the car relative to the road
Why is it important to know if your reference point is moving?
If your reference point is moving you will find it difficult to determine what direction you are moving or even if you are moving at all.
Relative Motion
Whether you are moving or not depends on your reference point. Are you moving while reading this book? No if your reference point is your chair - you are not changing position relative to your chair. But compared to the sun YOU ARE MOVING!
How do you know if an object is moving?
You know an object is moving if it changes its position relative to (compared to) a stationary reference point.
triangle of formulas
d s----t
Centi
one hundredth
Kilo
one thousand
Milli
one thousandth
Measuring Distance
the International System of Units - so communication is clear. Scientists use SI units to describe distance while describing motion. The meter is the SI unit for length and is a little over a yard in length.
