FREE FALL Lecture for 9/27/2007

Galileo and his Incline! Galileo showed that falling bodies move with constant acceleration This constant acceleration is due to… Rolled balls down inclines with various levels of steepness – why? What are some errors with Galileo’s experiment? Objects with different weight fall with the same constant acceleration – what must be insignificant? http://www.youtube.com/watch?v=eNn4yXEA_XQ

Galileo showed that falling bodies move with constant acceleration

This constant acceleration is due to…

Rolled balls down inclines with various levels of steepness – why?

What are some errors with Galileo’s experiment?

Objects with different weight fall with the same constant acceleration – what must be insignificant?

http://www.youtube.com/watch?v=eNn4yXEA_XQ

What does “free fall” mean? The motion of an object subject only to the influence of gravity Assume that the motion isn’t influenced by two factors… “ Fall” doesn’t necessarily mean the object is moving down As soon as it is released, an object is in free fall Acceleration produced by gravity on the Earth’s surface is symbolized as g g = +9.81 m/s 2 , never -9.81 m/s 2 If the positive direction is up, then a = -g If the positive direction is down, then a = +g

The motion of an object subject only to the influence of gravity

Assume that the motion isn’t influenced by two factors…

“ Fall” doesn’t necessarily mean the object is moving down

As soon as it is released, an object is in free fall

Acceleration produced by gravity on the Earth’s surface is symbolized as g

g = +9.81 m/s 2 , never -9.81 m/s 2

If the positive direction is up, then a = -g

If the positive direction is down, then a = +g

Do the Cannonball! A person steps off the end of a 3.00-m-high diving board and drops to the water below. How long does it take for the person to reach the water? What is the person’s speed on entering the water?

A person steps off the end of a 3.00-m-high diving board and drops to the water below.

How long does it take for the

person to reach the water?

What is the person’s speed on

entering the water?