CBSE Class 11-science Answered

Machines that use the mechanical properties of liquids are called hydraulic machines. Heavy machines like cranes, bulldozer etc use the property of low compressibility of liquids to lift heavy objects, dig the earth etc. Brakes in cars, trucks etc. also uses hydraulic machines.

Working:

In a hydraulic machine the force exerted by a piston on a small area is transmitted through a fluid (generally liquid) to another piston having a larger area that adds to the mechanical advantage of the larger piston. It is based on the Pascal's law, which states that change in pressure at any point in an enclosed incompressible fluid is transmitted undiminished to all points in the fluids. Example: A hydraulic lift is a machine that can lift heavy loads using hydraulic apparatus. This machine uses an incompressible fluid and its working is based on the Pascal's law.