help on physics?

Question

a pump under constant pressure uses 25000 joules of energy (work to move 30m squared of water. find the pump pressure required to do the work.

Answer 1

Energy = pressure * volume. I'll suppose you meant 30 cubic meters of water, not square meters. So 25000=30*P, P=833.3 N/m^2. If this isn't clear, imagine a 30m long horizontal tube of 1m^2 cross-section area filled with 30m^3 water. The pump effectively presses on the water column with a force of 833.3N for a distance of 30m, so the work done is 833.3*30=25000j.