Friday, April 25, 2008

Went over RA 5.1
Demo with blowpipes and marshmallows to show that longer cannons impart more impulse (same force, longer time) than short cannons.

Momentum Quiz

Demo with happy/sad balls knocking down block.

Intro to conservation of momentum: If no net external force acts on the system, then there is no change in momentum.

Conservation of Momentum has never been shown to fail. It does not apply in cases in which there is an external force, such as dropping an object.

Applied Conservation of Momentum to collisions.
Two basic types of collisions:
1. Elastic (Things bounce)
2. Inelastic (Things stick)
If there is no net external force, momentum is conserved in both types of collisions.

Demos with air track for both types of collisions.

Worked inelastic collision problems on board showing problems solving strategy.

Students worked on and handed in Elastic Collision Worksheet.

Homework: RA 5.3