Topic 3 Galileo: Return to Earth

1
Topic 3Galileo 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
Aristotles Laws of Motion

• 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
9
(No Transcript)
10
Aristotles fall
11
Galileos 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
16
(No Transcript)
17
Galileo observed

• D1 1 D1
• D2 3 D1
• D3 5 D1
• D4 7 D1

18
Galileo observed
19
(No Transcript)
20
Note increasing Velocity
21
Does it really work?
Distance time
(time)2 d/t d/t2
22
Our results
23
2 ramps?
24

25

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