**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***Preparation: Please start reading right after Example 10.9: read about tomato soup, and read Example 10.10 in your text in chapter 10.4.*

Please see 3.5 minute video: Parallel Axis Theorem

and some fun with Skateboarding loop de loop

In class: off to the races!

MT#2 Make up Question #4, collisions: elastic and inelastic

**Day 4: Precession**

See Veritassium’s Bullet into Block Video

Please see video describing Precession

MT#2 Make up Question #5, projectile motion