S-43 A.What is the relationship between the forces when the two sumo wrestlers run into each other? B.What is the relationship between their accelerations? C.Is their a relationship between their initial velocities and their final velocities?

Linear Momentum AP Physics Chapter 7

Linear Momentum 7.1 Momentum and Its Relation to Force

Linear momentum – product of an objects mass and its velocity Unit is a kgm/s The quantity is only useful when discussing collisions 7-1

7.1 Momentum and Its Relation to Force Impulse 7-1

7.1 Momentum and Its Relation to Force Impulse 7-1

7.1 Momentum and Its Relation to Force Impulse Or 7-1

7.1 Momentum and Its Relation to Force In a collision, to decrease force, we increase time of the collision Air Bags 7-1 Consumer Report

Linear Momentum 7.2 Conservation of Momentum

Two kinds of collisions 1.Perfectly elastic – objects bounce apart 2.Perfectly inelastic – objects stick together 7-2

7.2 Conservation of Momentum In reality collisions are a combination of the two. Law of Conservation of Momentum – in a closed system, momentum is conserved in a collision 7-2

7.2 Conservation of Momentum In an elastic collision Direction of velocity is given by the sign of the velocity. 7-2

7.2 Conservation of Momentum In an inelastic collision 7-2

7.2 Conservation of Momentum In an explosion The reverse of a Inelastic collision 7-2

S-44 Bart and his friends are out for a drive in their model T. The car and the passangers have a total mass of 560 kg. They run into an angry cow while driving at 6.08 m/s. If the car stops in 0.44 s What is the change in momentum of the car? What is the average force exerted on the cow?

S-45 Shortly after this picture was taken Mittens drove into a wall. The car had a mass of 2500 kg, was traveling at 30.2 m/s, and came to a stop in 1.9 m. A. What was the impulse on the car? B. What was the average force on the car?

Linear Momentum 7.3 Conservation of Momentum in Collisions

7.3 Conservation of Energy and Momentum Energy (mechanical) is conserved in an elastic collision So 7-3

7.3 Conservation of Energy and Momentum Any collision in which energy is lost, is considered inelastic. 7-3

Linear Momentum 7.4 Collisions in Two Dimensions

inelastic collisions in two dimension As always each dimension is treated independently Then use vector addition to calculate the final answer 7-4

S-46 In what would later be called a “really sucky play” Carlos came running out of the goal at 5.6 m/s and ran into the attacking Kanu. The 65 kg Kanu was running toward Carlos at 8.4 m/s. Carlos, who is 84 kg, came to a dead stop after the collision. What was Kanu’s velocity after the collision? Did you notice that Carlos missed the ball?

Linear Momentum 7.5 Center if Mass

7.5 Center of Mass Even if an object rotates there is one point that moves in the same that a particle would move if subject to the same force. 7-5

7.5 Center of Mass Center of mass – the point that does not rotate Center of gravity – the point at which the force of gravity can be considered to act 7-5 Java Applet