I'm working on a thought experiment. I want to know how much of the kinetic energy from a liquid mercury piston will be converted into work done on the hydrogen plasma in the form of compression, and how much work will be done on the piston in the form of compression. Note: assume piston walls are incompressible. A 5mm diameter, 5mm length liquid mercury projectile is to be fired down a barrel. The projectile is fired at 0.00002 mols of hydrogen plasma at 300000 Kelvin. The piston should ideally compress the plasma to the point at which fusion will occur. I am wondering if at higher pressures, when the hydrogen is already compressed into a very small volume, will almost all of the work be done on the piston as it will be able to change volume much more than the hydrogen? Following work = force*distance, at high pressures, the force will be equal on the piston and the hydrogen plasma but the piston will be able to change volume more than the hydrogen, correct? I know this is not the best defined problem but I am just looking for an idea of how to approach this problem.