1. Impulse and Momentum

2. Impulse-momentum theorem is applied to a single object
Impulse-momentum theorem is applied to a single object. The baseball has momentum – the bat supplies a force for a certain amount of time onto the baseball. OR the bat has momentum and the baseball applies a force for a certain amount of time onto the bat.

3. Hitting a baseball

4. Hitting a baseball

5. Hitting a baseball
Q: How can we determine the impulse?

6. Hitting a baseball Q: How can we determine the impulse?
Method-1: Knowing the average force ( ) and contact time (Δt), Impulse =

7. Hitting a baseball Q: How can we determine the impulse?
Method-1: Knowing the average force ( ) and contact time (Δt), Impulse =
Method-2: Impulse = Area under the Force versus Time graph.

10. Example
A baseball (m = 0.14 kg) has an initial velocity of v0 = –38 m/s as it approaches a bat. We have chosen the direction of approach as the negative direction. The bat applies an average force that is much larger than the weight of the ball, and the ball departs from the bat with a final velocity of vf = +38 m/s. Determine the impulse applied to the ball by the bat.

12. Captain America is 86 kg
Delta V of his body is from zero to 20 m/s
Ironman’s fist is in contact with his face for .05 seconds
With how much force did Ironman hit Captain America?

13. Conservation of Momentum (elastic)

14. Conservation of Momentum (inelastic)

15. “Backwards inelastic”

16. Momentum Problems Space Docking
First docking: Gemini 8 with the Agena Target Vehicle
Mass of Gemini: 3,175 kg Mass of Agena: 3,200 kg
Typical docking is .1 meters per second

17. Backwards Inelastic - Explosions
Suppose we have a 4-kg rifle loaded with a kg bullet. When the rifle is fired the bullet exits the barrel with a velocity of 300 m/s. How fast does the gun RECOIL backwards?

18. Assembling a Freight Train
A freight train is being assembled in a switching yard, and Figure 7.10 shows two boxcars. Car 1 has a mass of m1 = 65×103 kg and moves at a velocity of v01 = m/s. Car 2, with a mass of m2 = 92×103 kg and a velocity of v02 = +1.3 m/s, overtakes car 1 and couples to it. Neglecting friction, find the common velocity vf of the cars after they become coupled.

19. Ice Skaters
Starting from rest, two skaters “push off” against each other on smooth level ice, where friction is negligible. One is a woman (m1 = 54 kg), and one is a man (m2 = 88 kg). Part b of the drawing shows that the woman moves away with a velocity of vf1 = +2.5 m/s. Find the “recoil” velocity vf2 of the man.

20. One dimensional Motion Only For Our Class

21. Otherwise!