Ch. 9 Momentum and Its Conservation Milbank High School

Sec. 9.1 Impulse and Momentum Objectives –Compare the system before and after an event in momentum problems –Define the momentum of an object –Determine the impulse given to an object –Recognize that impulse equals the change in momentum of an object

Momentum What is momentum? The Minnesota Vikings have momentum entering the final weeks of the season… Anything that is moving has momentum Depends on what?

Momentum Momentum = mass * velocity In physics, the symbol for momentum is “p” sssooo… p = m * v kg·m/s Which has more momentum, a supertanker tied to a dock or a raindrop falling?

Momentum Determine the momentum of a... –60-kg halfback moving eastward at 9 m/s. 60 x 9 = 540 kg·m/s east –1000-kg car moving northward at 20 m/s x 20 = 20,000 kg·m/s –40-kg freshman moving southward at 2 m/s. 40 x 2 = 80 kg·m/s

Impulse and Momentum Impulse = Change in momentum Impulse –The product of the average net force exerted on an object and the time interval over which the force acts –Ns

Real Life Applications.. Sports… –Follow-through! –Gymnastics Mats Cars… –Airbags! –Before airbags…. –Bumpers Eggs… Jumping… –Knees –Shoes

Review Can a bullet have the same momentum as a truck?

Sec. 9.2 The Conservation of Momentum Objectives –Recognize the conditions under which the momentum of a system is conserved –Apply conservation of momentum to explain the propulsion of rockets –Solve conservation of momentum problems in two dimensions by using vector analysis

The Law of Conservation on Momentum The total momentum of two objects before a collision is equal to the total momentum of the two objects after the collision.

Two Particle Collisions –Inelastic collisions m A v A1 + m B1 v B1 = m A v A2 + m B v B2

Propulsions We can also use: p A2 = -p B2 m A v A2 = -m B v B2 Example Problem Pg. 212