1. The problem statement, all variables and given/known data A steel cylinder filled with water contains 3000psi of pressure, completely sealed, walls ≈ infinite thick. No gas is present inside of the cylinder, and no heat exchange. To the problem; if a solid rod/piston enters on top of the cylinder with no possibilities to bleeding off the pressure, what will the pressure build up be if the rod enters the cylinder with 1 ft? Height of cylinder 500ft, ID of cylinder 8,535in, OD of piston 4in, Temperature of water 333,15K→ Isothermal compressibility of water β= 3,0621e-6 [psi-1] 2. Relevant equations β=(1/V)*(∂V/∂P) F=P*A 3. The attempt at a solution Volume before entering the the piston V1= 35,4bbl, after V2 = 35,384 bbl Solved the above equation for P2 = P1 - ((V2-V1)/(V1*β)). This gave a new pressure inside the cylinder of 4429,9 psi. I think this pressure is too high compared to the displaced volume that the piston occupies. I am a bit uncertain if the equation above is correct to use for this situation. Please help, thank you.