Momentum

Newton's Apple : Video Clip Momentum: is the inertia of motion Momentum = mass x velocity momentum = mv = P

Impulse equals change in momentum The greater the force that acts on an object, the greater will be the change in velocity, and hence, the change in momentum. A long sustained force produces more change in momentum than the same force applied briefly. Impulse: force x time (N * s) Impulse = change in momentum Case 1: increasing momentum To increase momentum of an object, apply the greatest force you can and extend the time of contact as much as possible.

Case 2: Decreasing momentum over a long time If you want the force of impact to be small, extend the time of impact. Ex. Bending knees when you jump off something to the ground below. Case 3: Decreasing momentum over a short time. Making the time of contact very brief makes the force of impact huge. Ex. A karate expert breaking bricks.

Bouncing: impulses are greater when bouncing takes place. Law of Conservation of momentum: In the absence of an external force, the momentum of a system remains unchanged. Collisions Elastic collisions: momentum is transferred. Objects are not permanently deformed and don’t generate heat.

Inelastic collisions: objects become distorted and generate heat; objects become tangled or couple together. P96 fig Answers questions 1-3. YouTube - Newton's cradle - Newtonin kehto YouTube - Spectacular 1913 Train Collision YouTube - inelastic collision Momentum vectors Momentum is conserved even when colliding object move at an angle to each other. P98 fig 7-15.

Classwork answer questions p99 #1-20

Momentum