Isaac Newton. Initial calculations didn’t work.

Isaac Newton

Isaac Newton

Isaac Newton

• Initial calculations didn’t work

Isaac Newton

• Initial calculations didn’t work

• Placed theory in a drawer for 20 years

Isaac Newton

• Initial calculations didn’t work

• Placed theory in a drawer for 20 years

• When the comet of 1670 came, Halley convinced him to re- look at it.

Isaac Newton

• Initial calculations didn’t work

• Placed theory in a drawer for 20 years

• When the comet of 1670 came, Halley convinced him to re- look at it.

• Produced the Law of Universal Gravitation

Law of Universal Gravitation

F ~ m1m2

d2

F = G x m1m2

d2

G = 6.67 x10-11 N m2 / kg2

Universal gravitation constant

(G) = 6.67 x10-11 N m2 / kg2

• Equals the force of attraction between two 1kg masses 1 meter apart

Universal Law of Gravitation

• Youtubehttp://www.youtube.com/watch?v=NPyH93vXutk

http://www.youtube.com/watch?v=D5BQkdyAw8A

Universal gravitation constant

• Philipp von Jolly’s – measurement experiment

• Mercury Flask and a 6 ton lead ball

Gravitational Force

• The force is extremely small and for most tangible things it is two sensitive to measure

• attraction to one another is not measurable but the attraction to the earth is what we call weight

Gravitational Force

• It is based on the distance to the center of the earth –

• weigh less on a mountain

• Is this a new diet infomercial???

Inverse Square Law

Book Questions1.By how much does the gravitational force

between two objects decrease when the distance between their centers is doubled, tripled, and increased tenfold?

2.Consider an apple that is at the top of a tree and is being pulled by the earths gravity with a force of 1 N. If the tree were twice as tall, would the force of gravity be only ¼ as strong?

Tides

Tides

Spring Tides

Higher Than Average tides and

lower than average tides

Neap Tides High tides lower than average and

low tides higher than average

People Tides?