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Calculating Entropy of a Star using Heat Capacity

by khfrekek92
Tags: energy, entropy, star, temperature
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khfrekek92
#1
Feb6-12, 05:04 PM
P: 76
1. The problem statement, all variables and given/known data
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).


2. Relevant equations
dS=C*dT/T



3. 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!
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phyzguy
#2
Feb6-12, 05:50 PM
P: 2,179
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%...trode_equation
khfrekek92
#3
Feb6-12, 06:18 PM
P: 76
That is what I was thinking too, but the problem specifically states that you need to use the heat capacity to determine the Entropy. :(


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