1. Momentum & Impulse

2. Words used in everyday life. A football team or a politician running for office is said to have momentum. If you have the urge to do something, your impulsive. In physics they have a slightly different meaning.

3. Impulse Impulse = the product of a force exerted on an object and the time interval over which the force acts. Impulse = FΔt Units = N·s

4. Momentum Momentum = the product of the mass and the velocity of an object (p). p = mv Units = kg·m/s Momentum increases when mass OR velocity increases. ??? Can a bullet and an airplane have the same amount of momentum???

5. Impulse – Momentum Theorem If you want to know how a force that acts on an object effects its momentum…combine the two ideas. Impulse – Momentum Theorem FΔt = mΔv Or FΔt = p f – p i

6. Impulse – Momentum Theorem (cont.) Used to show the transfer of force between objects. Ex #1 = Golf ball hit against steel wall (approx. 75 mph)

7. Impulse – Momentum Theorem (cont.) Ex #2 = Golf ball hit against steel wall (approx. 150 mph)

8. Impulse – Momentum Theorem (cont.) I – M Theorem can be used to save your life. How??? A large change in momentum occurs when there is a large impulse. A large impulse occurs from: 1. a small force acting over a long period 2. a large force acting over a short period

9. Impulse – Momentum Theorem (cont.) What happens when you hit a tennis ball? A small force, but due to follow through it acts on the ball for a long time.

10. Impulse – Momentum Theorem (cont.) What happens in a car crash? A large force that acts on the object for a short period of time

11. Impulse – Momentum Theorem (cont.) An air bag actually increases the time you are in contact with the object (steering column) and therefore decreasing the impulse force.