Writing Prompt: 10/26/2006 Predict what will happen if a 250 lb. safety runs into a 140 lb. punt returner who was standing still to catch a punt during a football game? Write down what will happen to the safety and what will happen to the returner (think about speed and motion)

Transfers and Collisions Momentum Transfers and Collisions

Momentum What is it? In general terms: It is when an object picks up speed. To gain momentum you are gaining speed.

Momentum What is it? Mathematically: Momentum = Mass X Velocity p = mv = constant (lower case “p” stands for momentum)

Momentum What is the unit for momentum? Momentum = Mass X Velocity Mass (kg) X Velocity (m/s) = kg-m/s Unit is a “kilogram meter per second”

Momentum QUESTION: What is the momentum of a 60 kg Running back running at 3 m/s? ANSWER: 60 kg x 3 m/s = 180 kg-m/s

Conservation of Momentum Collisions: Two different types Elastic: Colliding objects DON’T stick together Example: Bouncing a ball Plastic: Colliding objects combine into a single object Example: Firing a bullet into a wood block

Conservation of Momentum If a collision occurs, MOMENTUM IS CONSERVED!!! Example: If the van hits the car, the final momentum of the two cars will equal their initial momentum!!!

Conservation of Momentum Let’s see a demonstration…

Conservation of Momentum QUESTION: What is the final momentum if a 100 kg cart moving at 3m/s hits another 100 kg cart that isn’t moving and they stick together? ANSWER: 300 kg-m/s 100 x 3 + 100 x 0 = 300

Conservation of Momentum QUESTION: What is the final VELOCITY of the system if a 100 kg cart moving at 3m/s hits another 100 kg cart that isn’t moving and they stick together? ANSWER: 1.5 m/s 300 kg-m/s = m x v = 200 kg x v v = 300/200 = 1.5

Conservation of Momentum Let’s see another demo…

Conservation of Momentum Answer the following questions in your comp book from Mr. Darling