Monday, November 15, 2010

Monday, November 15, 2010

Handed back tests and went over any questions. Numbers on test are percent out of 100 and number correct out of 43. In my gradebook I scaled the test scores and entered them out of 70

Handed back journals. The maximum score was 60 but I put them out of 50 in my gradebook. I talked about the journals. The main purpose is to have a description of the demos and how they relate to the concepts. Several students are just using the journal as a notebook and ignoring the demos all together. I asked for more focus on the demos for this quarter.

Angular equivalents to linear terms:
velocity <=> angular velocity (omega)
inertia (mass) <=> rotational inertia (I)
momentum (p=m*v) <=> angular momentum = I * omega
kinetic energy = 1/2 m * v2 <=> rotational KE = 1/2 I omega2

Day at the Races
Demos: Baseball bat and ankle weights
Race 1: Hoop vs Disc
Race 2: Plastic disks with ball bearings inside
Race 3: Shiny ball vs Go Car
Race 4: Broth vs Beans

Students voted on outcomes

Conservation of momentum <=> conservation of angular momentum

If no net external torque acts on the system (if nothing messes with the system from outside) then there is no change in the angular momentum of the system.
Demo: weights on spinning plate

Handed out RA 11.2 due tomorrow
Students will also write up demos in their journals

Finished with bicycle wheel on spinning platform and then gyroscopic bicycle wheel.

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