The entropy sof a system of n particles at a temperature t is given by...
Given:
- Entropy of a system of n particles at temperature t is given by s = a(nvu)^(1/3)
- u and v are the internal energy and volume of the system, respectively
- a is a constant
To find:
- Internal energy of the system when the temperature changes to 4t at constant volume
Solution:
Step 1: Relationship between Entropy and Temperature
The entropy of a system is related to the temperature through the equation:
ΔS = ∫(dQ/T)
Step 2: Entropy Change at Constant Volume
At constant volume, the heat transfer can be written as:
dQ = dU (change in internal energy)
Substituting this in the entropy equation:
ΔS = ∫(dU/T)
Step 3: Calculating the Change in Internal Energy
Using the given expression for entropy:
s = a(nvu)^(1/3)
Taking the derivative of s with respect to u:
ds/du = a(1/3)(nvu)^(-2/3) * nv
Rearranging the equation:
du = (3/(anv)) * (nvu)^(2/3) * ds
Step 4: Calculating the Internal Energy
Substituting the above expression for du in the entropy equation:
ΔS = ∫(dU/T)
ΔS = ∫(3/(anv)) * (nvu)^(2/3) * ds / T
Rearranging the equation:
ΔS = (3/(anvT)) * ∫(nvu)^(2/3) * ds
Integrating both sides:
ΔS = (3/(anvT)) * (3/5) * (nvu)^(5/3) + C
Where C is the constant of integration.
Step 5: Finding the Internal Energy
At constant volume, the change in entropy is given by:
ΔS = ∫(dU/T)
Substituting the expression for entropy:
(3/(anvT)) * (3/5) * (nvu)^(5/3) + C = ∫(dU/T)
Since the volume is constant, dv = 0. Therefore, the integral simplifies to:
(3/(anvT)) * (3/5) * (nvu)^(5/3) + C = ∫(dU/T) = (1/T) * ∫dU
Integrating both sides:
(3/(anvT)) * (3/5) * (nvu)^(5/3) + C = (1/T) * U
Simplifying the equation:
(3/(anvT)) * (3/5) * (nvu)^(5/3) = (1/T) * U - C
Since entropy is given by s = a(nvu)^(1/3), we can substitute this expression:
(3/(anvT)) * (3/5) * s^(5/3) = (1/T) * U - C
At temperature 4t, the entropy becomes:
s' =