# Homework Help: Solid Compressability

1. Aug 7, 2010

### dacruick

1. The problem statement, all variables and given/known data

Hello, I have a problem involving a copper block of mass .25kg. They have a given compressibility due to pressure change, and compressibility due to temperature change. They give the density for copper as well. They tell you that the pressure changes from P1 --> P2 isothermally.

It then asks what the amount of heat leaving the system is
The work done on the copper block
and the total change in internal energy

2. Relevant equations

3. The attempt at a solution

what I've done already is figured out the volume change due to the pressure change.

Using this volume change I can theoretically find the work done using -nRT*ln(Vf/Vi). The only problem is I don't have a value for the moles. I could find it if i had the molar mass of copper, but I don't, and this is a practice exam problem.

If i assume that because temperature change is 0, the change in internal energy is 0. Then heat will equal negative work. but i have a strong feeling this is wrong.

2. Aug 7, 2010

### zhermes

In an isothermal process, the work done is simply the pressure times the change in volume, i.e.
$$W = P\Delta V$$
Does that help?