## PHYS 317 - Reading Assignment #1

Read sections 1.1-1.3, and answer the following questions by email (bvollmay@bucknell.edu), hardcopy, or web form before class Friday, Aug 29.

1. What is the relation (analogous to the ideal gas law) between the pressure and the average velocity?

Eq. (1.14), P = N m < vx2 >, where <.> means ``average'' (I don't know how to make an overline in html). Equivalently, you could use the velocity instead of the x-component with P = N m < v2 > /3, where <.> means ``average''

2. Is equation (1.20) true for non-ideal gasses?

Yes, oddly enough. We'll learn why later.

3. Does a diatomic molecule have a higher or lower thermal energy than a monatomic molecule?

Higher. U = (5/2) N k T for a diatomic molecule (assuming the bond isn't oscillating) and U = (3/2) N k T for a monatomic molecule.

4. What is the average thermal energy for a diatomic gas at very high temperatures (neglecting relativity)?

When the bond begins to oscillate, which is usually much higher than room temperature, then there are 7 degrees of freedom instead of 5, so U = (7/2) N k T.