Hydraulic Jack

A hydraulic jack is a hydraulic device consisting of two pistons with a fluid, typically hydraulic oil (which has minimal compressibility), sealed between them. The operation of the hydraulic system is governed by Pascal's Law, which states that pressure applied to a fluid in a sealed system is transmitted equally in all directions throughout the liquid. In a hydraulic jack, a force F₁ is applied to the surface S₁ of the first piston, generating pressure ρ in the fluid. This pressure is uniformly distributed throughout the liquid and also acts on the second piston. The pressure ρ exerts an equal force per unit area on the surface S₂ of the second piston. The resulting force F₂ on the second piston depends on the size of its surface area, S₂. As a result, the force applied can either be increased or decreased depending on the relative sizes of the piston areas. When lifting a load, such as a car, with a hydraulic jack, a smaller force F₂ is applied to the smaller piston over a longer distance s₂. Conversely, the larger piston generates a greater force F₁ over a shorter distance s₁. These changes in force and distance are consistent with the golden rule of mechanics, which maintains that any increase in force is offset by a proportional decrease in distance, and vice versa. This allows hydraulic systems to effectively multiply force, making heavy lifting possible with minimal effort.