Impulse and Momentum

1. Impulse and Momentum

2. Notebook pg#41 - Momentum • EQ: How are Momentum and Impulse expressed, and what factors contribute to momentum and impulse? • LO: We will investigate the components of momentum and impulse and apply them to solve word problems. • CT: I will summarize the formula for momentum and impulse in words, and do practice problems calculating momentum and impulse.

3. Momentum • Mass in motion Momentum is directly proportionalto an object's mass and directly proportional to the object's velocity. p ~ m and p~v

4. Momentum Equation: Momentum = mass x velocity P = mv

5. Large Momentum Examples • Huge ship moving at a small velocity • High velocity bullet P = Mv P = mv Now complete 1-7 on your worksheet (3 min)

6. Sample Problem 1 • The world’s most massive train ran in South Africa in 1989. Over 7 km long, the train traveled 861.0 km in 22.67 h. Imagine that the distance was traveled in a straight line north. If the train’s average momentum was 7.32 x 108 kg•m/s to the north, what was its mass? hints: convert distance convert time manipulate equation

7. Sample Problem 1 The world’s most massive train ran in South Africa in 1989. Over 7 km long, the train traveled 861.0 km in 22.67 h. Imagine that the distance was traveled in a straight line north. If the train’s average momentum was 7.32 x 108kg•m/s to the north, what was its mass?

8. Sample Problem 2 • One of the smallest planes ever flown was the Bumble Bee II, which hada mass of 1.80 × 102 kg. If the pilot’s mass was 7.0×101 kg, what was the velocity of both plane and pilot if their momentum was 2.08×104 kg•m/s to the west? hints: use the total mass of both the plane and the pilot. manipulate the equation

9. Exit Slip What factors determine momentum? How do these factors affect each other? Write a sentence in which you include the word momentum.

10. IMPULSE

11. Impulse • Impulse -amount of force needed to stop an object’s momentum in a specific amount of time. Units N·s I = FΔt https://www.youtube.com/watch?v=s6QR0KdyTFY&feature=relmfu

12. Momentum and Impulse Theorem

13. Momentum and Impulse Theorem • What does momentum and impulse have to do with each other? • Momentum = mv • If velocity changes, momentum changes, and acceleration (either + or –) occurs • But we know: • for acceleration to occur, a force has to be applied. • If a given force is applied over a longer time, more acceleration occurs. • IMPULSE is a measure of how much force is applied for how much time, and it’s equal to the change in momentum.

14. Momentum and Impulse Theorem Impulse = Force x time A force applied over time will change the momentum of an object: FΔt = Dp Impulse = Change in momentum

15. Momentum and Impulse Theorem Newton’s Second Law can read F = ma FΔt = DpFΔt = pf–pi  FDt = mvf-mvi Impulse = Change in momentum

16. Case 3: Decreasing Momentum over a Short Time If the boxer moves away from the punch, he extends the time and decreases the force while stopping the punch. If he moves toward the punch, he decreases the time and increases the force The airbag extends the time over which the impulse is exerted and decreases the force. Hitting the bricks with a sharp karate blow very quickly maximizes the force exerted on the bricks and helps to break them.

17. Decreasing Momentum over a long time • Increase Dt and minimize the force • Catching a ball • Bungee jumping • Air bags • Seat bealts FDt

18. Momentum and Impulse • Momentum is mass in motion • Impulse is how much force is applied for a given time on an object P = mv • Putting it altogether: • The amount of force applied over a given time changes the object’s momentum FΔt = Dp I = FΔt