Calculating Entropy of a Star using Heat Capacity

[khfrekek92]

Homework Statement

Using the viral theorem, the heat capacity of a star is given as C=-3*k/2.
Using this, I need to calculate the entropy of a star in terms of the average temperature T, then in terms of U (total energy).

Homework Equations

dS=C*dT/T

The Attempt at a Solution

To solve for S, I integrated getting S=-(3/2)*k*ln(tf/ti)+C. How do I solve this for S? This function is undefined when Temperature is 0...

Thanks in advance!

 

[phyzguy]

Since a star is close to being an ideal gas, you should be able to use the Sackur-Tetrode equation to calculate its entropy.

http://en.wikipedia.org/wiki/Sackur–Tetrode_equation

 

[khfrekek92]

That is what I was thinking too, but the problem specifically states that you need to use the heat capacity to determine the Entropy. :(