# Work done by gas

In this we have to find work done by the gas .

I thought

work done by gas = work done by spring

work done by gas = $\frac12kx^2$

but my sir told me that I have made some conceptual mistake, I could not understand what ?

• My sir told me the answer as work done by the gas is $5[PV-kx^2 -kxV/S]/2$ – search Apr 23 '17 at 14:33

Change in volume of gas $$\Delta V= \text{cross-sectional area of piston}\times \text{change in position of piston}=S\times x_0$$
• Okay read it, but you have to show your working first. Think about all the energy contributions by the gas. $PV$ is an energy term, so is $\frac{1}{2}kx^2$ etc. – BLAZE Apr 23 '17 at 14:38