1. Why the Principle of Relativity is necessary.

5. Newton’s Laws  1. Law of Inertia: Every body continues in its state of rest, or of uniform motion in a straight line, unless it is compelled to change that state by forces impressed upon it.  2. Law of Motion: The change of motion is proportional to the motive force impressed; and is made in the direction of the right line in which that force is impressed.  F=ma  3. Law of Action and Reaction: To every action there is always opposed an equal reaction; or the mutual actions of two bodies upon each other are always equal and directed to contrary parts.

6. The Spinning Bucket

7. Water moves towards the edges.

8. Newton’s Bucket experiment

9. Newton’s Bucket Experiment StageMotionsPerceived Forces (Water drawn towards edge?) Motion observed. (Observing wall of bucket) 1: Let Bucket Spin Bucket Moves Water still NoYes 2:Both Spinning Bucket Moves. Water Moves YesNo 3:Stop Bucket Bucket Still Water Moves Yes 4:Both Stopped Bucket Still Water Still No