FREE FALL AND PROJECTILE MOTION

ARISTOTLE Aristotle thought heavy objects fall quicker than lighter objects.1. Aristotle was ancient Greek philosopher who sat

around thinking about pretty much everything, including the joys of physics.

2. He used reasoning to try and work out how the world worked from everyday observations.

3. One of his famous theories was that if two objects of different mass are dropped from the same height, the heavier object would always hit the ground before the lighter object.

GALILEOGalileo thought all objects in free fall accelerate uniformly.1. Galileo thought that all objects accelerate towards the

ground at the same rate – so objects with different weights dropped from the same height should hit the ground at the same time.

2. Not only that, but he thought the reason objects didn’t seem to do this was because of the effect of air resistance on different objects.

3. Believe it or not, scientists don’t think Galileo chucked stuff from the top of the leaning tower of Pisa to test this theory. Instead he did an even more exciting experiment – he rolled balls down a slope!

Galileo tested his theories using experiments.

• Not only did Galileo disagree with Aristotle on almost everything, he liked to shout it from the rooftops. He not only managed to insult other philosophers at the time, but the pope and the entire catholic church too – which got him in a lot of trouble!

• Even though he was so unpopular, Galileo's theories eventually overturned Aristotle's and became generally accepted.

EXAMPLEMonty fires a scale model of a TV talent show presenter horizontally with a velocity of 100m/s from 1.5m above the ground. How long does it take to hit the ground, and how far does it travel?

You know u=0, s=-1.5m, a=g=-9.81. Use s=1/2t== 0.55s Speed=distance/time Distance= speed x time = 55m