1. Topic 3 Galileo: Return to Earth

2. Aristotle BC 384-322

3. Four Elements Earth Water Air Fire Aether

4. Natural Motion: Elements tend to seek their natural place. Violent Motion: Any forced motion that opposes natural motion. (Push or Pull) The speed of a moving object is directly proportional to the force moving it.

5. Aristotle’s Laws of Motion 1.Rest is the natural state of an object. 2. Heavier things fall faster, the speed proportional to the weight.

6. Some definitions: Displacement= distance the object covers and the direction it came from… Velocity= change in displacement in time (note: it is speed AND direction) Speed is only how fast the object moves Acceleration= change in velocity in time.

7. Galileo Galilei (1564-1642)

8. Two New Sciences

10. Aristotle’s fall

11. Galileo’s fall

12. A thought experiment GIVEN: three identical weights dropped from the same height

13. Does a ten pound weight fall ten times faster than a one pound weight?

14. Can Galileo measure free fall?

15. Dilute the process

17. Galileo observed D 1 = 1 D 1 D 2 = 3 D 1 D 3 = 5 D 1 D 4 = 7 D 1

18. Galileo observed

20. Note increasing Velocity

21. Does it really work? Distance time (time) 2 d/t d/t 2 150.001.00 150.00 125.000.910.83 137.36150.95 100.000.810.66 123.46152.42 75.000.700.49 107.14153.06 50.000.570.32 87.72153.89

22. Our results

23. 2 ramps?

25. Rest was not a natural state. The concept of inertia was introduced.