This document discusses pressure and moments. It begins by defining pressure as force per unit area and explains that higher pressure results from concentrating force over a smaller area. Pressure in liquids increases with depth due to gravity. Hydraulic systems use incompressible fluids to transmit pressure throughout the system. A moment is the turning effect of a force about a pivot, and it can be increased by applying force further from the pivot or increasing the force. The principle of moments states that balanced objects have equal and opposite clockwise and counter-clockwise moments.