1. Ch. 12 Sec. 3 Newton’s 3 rd Law

2. Newton’s 3 rd Law of Motion All forces act in pairs Whenever one object exerts a force on a second object, the second object exerts an equal & opposite force on the first.

3. Action-Reaction Action-reaction forces do not cancel They act on different objects Ex. Swimmer action on the water Reaction on the swimmer

4. Momentum Product of an objects mass and velocity Momentum = Mass x Velocity p = m x v Ex: Bowling ball Momentum = 7.0 kg x 6.0 m/s Momentum = 42 kg · m/s

5. Momentum Brett Favre is considered one of the fastest throwing QB’s. How much momentum does one of his “laser” passes have if a 0.30 kg football has a velocity of 17.5 m/s?

6. Law of Conservation of Momentum Loss of momentum of one object equals the gain in momentum in another Momentum is conserved p 1 = p 2 m 1 v 1 = m 2 v 2

7. Law of Conservation of Momentum A billiards player strikes his cue ball with a mass of 0.17 kg with a velocity of 3.9 m/s. What is the mass of the 8 ball if it responds with a 4.1 m/s velocity?

8. Centripetal Force Center-directed force that continuously changes the direction of an obect Moves in a circle Earth, moon, tides