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Momentum and impulse

Momentum and impulse. Let’s start with everyday language. What do you say when a sports team is on a roll? They may not have the lead but they may have ___________ MOMENTUM A team that has momentum is hard to stop. What is momentum?. Momentum: p=mass x velocity

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Momentum and impulse

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  1. Momentum and impulse

  2. Let’s start with everyday language • What do you say when a sports team is on a roll? • They may not have the lead but they may have ___________ MOMENTUM • A team that has momentum is hard to stop.

  3. What is momentum? • Momentum: p=mass x velocity • What does this mean in the physical world? • Which is harder to stop a soccer ball or a bowling ball moving at the same speed? Explain why? • What about a bullet? Explain why?

  4. Momentum • Momentum is a vector quantity.

  5. What is Conservation? • Conserved describes a quantity that may change during some process, but does NOT appear from nowhere or disappear without a trace. • In an isolated system, certain physical quantities are conserved, such as mass and energy. • Let’s see how it works!

  6. How can we represent conservation?

  7. Is Momentum Conserved? • When there is a collision between two objects, Newton's Third Law states that the force on one of the bodies is equal and opposite to the force on the other body.  • Therefore, if no other forces act on the bodies (in the direction of collision), then the total momentum of the two bodies will be unchanged. • Hence the total momentum before collision in a particular direction = total momentum after in a particular direction.

  8. What happens during a collision?

  9. Types of Collisions

  10. To change the momentum of a body, a force must be applied to the mass. The longer this force is applied to the mass, the greater effect it will have on changing the momentum. F∆t = ∆(mv) IMPULSE– A force applied for a period of time which results in a change of momentum

  11. Why does an egg break or not break? • An egg dropped on a tile floor breaks, but an egg dropped on a pillow does not. Why? FΔt= mΔv In both cases, m and Δv are the same. If Δt goes up, what happens to F, the force? Right! Force goes down. When dropped on a pillow, the egg starts to slow down as soon as it touches it. A pillow increases the time the egg takes to stops.

  12. Car Crash Would you rather be in a head on collision with an identical car, traveling at the same speed as you, or a brick wall? Assume in both situations you come to a complete stop. Take a guess! http://techdigestuk.typepad.com/photos/uncategorized/car_crash.JPG

  13. Car Crash (cont.) The answer is… It Does Not Matter! Look atFΔt= mΔv In both situations,Δt, m, andΔv are the same! The time it takes you to stop depends on your car, m is the mass of your car, and Δv depends on how fast you were initially traveling.

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