Hydraulic systems like the hydraulic jack are based on Pascal's law. It consists of a U-shaped tube having columns of unequal area of cross-section. Piston A is fitted onto the smaller column, while piston B is fitted onto the larger column. The tube is filled with a fluid such that it attains the same height in both the columns. When a force is applied to piston A, it exerts a pressure p1 on the fluid. According to Pascal's law, this pressure is transmitted to piston B through the fluid due to which piston B is pushed outward. The pressure p2 felt by piston B is equal to p1. Now, using the relationship between pressure and force, an expression for the forces in a hydraulic system is obtained provided that the friction in the system is negligible. The output force can be increased in the hydraulic system by applying a force on a smaller area.