# Week 9 Rotational Systems

Week 9:
Rotational Systems, Rotational Collisions

Day 1: sum of the forces = m*a, for centripetal acceleration
Preparation: Besides finishing PS 8 and preparing for any extra MT2 question, please see this super short video: Bucket of Water over your Head
MT#2 Make up Question #1, systems of masses with friction
Hand in PS #8
Come in with:
1) Why does the water stay in the bottom of the bucket?
2) Why is the average acceleration of Mike less than “v squared over r”
Take away Concept: When dealing with circular motion, the dynamics are just the same as always: the vector sum of the forces = m*a. The only difference is that “a” is centripetal acceleration.

Day 2: Rotational Collisions

Preparation: Please read chapter 10.6 – Collisions of Extended Bodies Two Dimensions. The most important concept we want to take away from reading this is that a moving mass has angular momentum about a rotation center = mvR = pR, where “R” is the perpendicular distance between the rotation center and the velocity direction of the moving mass.

See 2 minute video, Which block goes higher?
See 2 minute video, See which block goes higher!

MT#2 Make up Question #3, inclined plane, friction, work, and energy

Day 3:Day at the Races and the parallel axis Theorem