Demonstrations tomorrow: pendulum and quantum physics

Tomorrow (Thursday) we will have a demonstration and measurements of the periodic behavior of pendula. Amanda and Rylee will be taking digital video, too, for iTunes U and YouTube.

We will also map out the momentum of the pendulum and build a foundation for the quantum physics on our agenda for the last three weeks of the semester.

Homework, lovely homework

To augment your weekend pleasure and recreation, I have activated a momentum homework assignment, due on Monday. It is Homework #9.

I will have some green jello questions on HW #10, next Monday, so make sure to read up on chapter 6!

Today's mini-review CPS session is UP

Check the Linsky files for today's CPS session.

To recap, the toughest question was the size of Δp.

Δp = p_f - p_i and we know its direction is rightward.
p_i = (1 kg m/sec left, 1 kg m/sec down)
p_f = (1 kg m/sec right, 1 kg m/sec down)

Subtract horizontal components, final - initial:
     1 kg m/sec right - 1 kg m/sec left
which is just like
     +1 kg m/sec - (-1 kg m/sec)
and that totals +2 kg m/sec, which is the answer.

Note: the vertical components do not change at the impact, so Δp = 2 kg m/sec rightward and nothing vertical.