Pascal.s Law : Pressure in a fluid at rest is same at all points which are at the same height . A change in pressure applied to an enclosed fluid is transmitted undiminished to every point of the fluid and the walls of the containing vessel .
Hydraulic lift is based on this principle.
As shown in figure the cylinders of cross section areas are `A_(1)andA_(2)(A_(1)ltltA_(2))`. In both cylinder air tight pistons are lifted.
Schematic diagram illustrating the principle behind the hydraulic lift , a device used to lift hevay loads.
A liquid is filled in this vessel.
A piston of small cross section `A_(1)` is used to exert a force `F_(1)` directly on the liquid . The pressure` P_(1)=(F_(1))/(A_(1))`is transmitted throughout the liquid to the large cylinder attached with a liner piston of area `A_(2)`. The force `F_(2)` is exerted on piston in upward direction Due to this force, pressure on piston is `P_(2)=(F_(2))/(A_(2))`.
From pascal law `P_(1)=P_(2)`
`therefore(F_(1))/(A_(1))=(F_(2))/(A_(2))`
`thereforeF_(2)=((A_(2))/(A_(1)))F_(1)`
`A_(1)ltltA_(2),thereforeF_(2)gtgtF_(1)`
Hence by small force `F_(1),F_(2)` will be obtained .
By this device car or truck placed on a platforms can be lifted easily.
