Pascal’s Principle and the Hydraulic Lever
shows how Pascal’s principle can be made the basis of a hydraulic lever. In operation, let an external force of magnitude F, be directed downward on the lefthand (or input) piston, whose area is Aj. An incompressible liquid in the device then produces an upward force of magnitude F; on the righthand (or output) piston, whose area is A”. To keep the ystem in equilibrium. there must be a downward force of magnitude F” on the output piston from an external load (not shown). The force F: applied on the left and the downward force F” from the load on the right produce.
The product of force and distance remains unchanged so that the same work is done. However, there is often tremendous advantage in being able to exert the larger force. Most of us, for example, cannot lift an automobile directly but can with a hydraulic jack, even though we have to pump the handle farther than the automobile rises. In
this device, the displacement d, i accomplished not in a single stroke but over a series of small strokes.