motion scientists. aristotle aristotle: greece- 335-325 b.c. what he said people believed because he...
TRANSCRIPT
Motion Scientists
Aristotle
• Aristotle:• Greece- 335-325 B.C.• What he said people
believed because he was well educated
Aristotle
• Gravity: heavier objects fall faster than light objects • Experiment: Dropped rock and feather at the same
time, the rock hit the ground first• Motion: objects only move if you push/pull them,
and objects only stop if you stop pushing/pulling them (*did not mention outside forces)
• His ideas lasted for about 2000 years = BIG DEAL! That is a LONG time to be considered correct
Galileo
• Italy- early 1600s• “Renaissance Man” – good at many things• Challenged Aristotle’s ideas
Galileo
• Gravity: objects fall at the same rate regardless of mass
• Experiment: dropped a 3 pound cannon ball and a 5 pound cannon ball from the same height (Tower of Pisa) at the same time, and both hit the ground at the same time
• This experiment shows the opposite of Aristotle’s idea
Galileo
• Motion: objects in motion stay moving until an “invisible force” or another object stops them (“invisible forces” friction!)
• NOTICE: this concept is like Newton’s 1st Law• Galileo is credited with idea of “inertia”• Inertia is the resistance to a change in motion
Aristotle & Galileo
• NOTICE: At this point, neither person has mentioned air resistance!
Newton
• England, late 1600s• Was Galileo’s student,
so used Galileo’s ideas and added to them
• Combined Aristotle and Galileo’s ideas
Newton
• Gravity:– Objects fall at the same rate regardless of mass, in the
absence of air resistance• Motion: 3 Laws1. Law of inertia (object in motion stays in motion,
object at rest stays at rest, until outside force)2. Force = mass x acceleration
**need more force to move a larger mass!
3. For every action, there is an equal and opposite reaction