Hi all ... thanks in advance to anyone who helps me out ...it should be simple , i need some formulas .. for example 1. Find the mass of an cargo that can be moved by using a hydraulic piston pump if D=1,7m and d=400mm=0,4m and force is 300hN. If force goes up by 10% find the pressure and new mass I remember the main one F1/d1^2= F2/d2^2 It's easy to find F2 but how to find a mass and pressure? Is pressure p = F2/A2 where A2 is D^2*Pi / 4 ??? and how to find this "d" in A2 ? And second question is on which pressure will NH3 have density of 1.65g/dm3 if temperature is -30C or 243,15K pV=nRT .. right? Or how many liters of gass can we get if volume of gass, on temperature of 333,15K and p of 0.7, is 250l.