- #1

mooshasta

- 31

- 0

## Homework Statement

Consider a rubber band for which the tension, [itex]f[/itex], as a function of temperature [itex]T[/itex] and length [itex]L[/itex] is [itex]f = \kappa T (L+\gamma L^2)[/itex], where [itex]\kappa[/itex] and [itex]\gamma[/itex] are positive constants. Determine the heat flow between it and its surroundings when the rubber band is stretched reversibly and isothermically from length [itex]L_1[/itex] to length [itex]L_2[/itex].

## Homework Equations

[tex]dE = TdS + fdL + \mu dN[/tex]

## The Attempt at a Solution

I think the question is asking to find [itex]\left( \frac{\partial E}{\partial L} \right)_{T,N}[/itex] and integrate that. I'm not sure how to get this quantity, though, since I don't know what entropy is. Can I use the Helmholtz free energy when calculating heat transfer? I don't think so, since they are not equal...

Thank you for your help!