Two kinds of forces

1
Two kinds of forces

• Contact forces you push me
• Field forces parachutist gets pulled down by
  earth

2
I dream of Jeannie

• Nugget of gold
• How does earth know?
• Magnet by other magnet
• How does magnet know?
• Charged particle by other
• How does charge know?

3
Big mass, big charge

• Earth big force on a big mass elephant
• Small force on small mass ant
• Same with charges

4
Gravitation field

• Earth alone has a gravitational field, just ask
  any dinosaur about the meteor that got captured
  in it 60,000,000 years ago
• Earth waits in shadows for a mass to come by
• Charge has a force field too
• Waits for another charge to come by
• NO CONTACT REQUIRED!

5
Mapping

• You can map gravitational fields 22,000 miles
  away
• Earth pulls left
• Moon pulls right
• Sun right
• Add them together
• Repeat at several locations, a map!
• Electric field mapping is same