Pascal’s Principle
Blaise Pascal based his law on the fact that
liquids cannot be (easily) compressed.
It states
“Pressure applied to an enclosed liquid is
transmitted equally to every part of the liquid
and the walls of the container”
Pascal used his law to design the hydraulic press.
A small downward force applied to the small
moveable piston can produce a large upward
force on the large moveable piston.
According to Pascal’s Principle, the pressure on
the small piston (ps) equals the pressure on
the large piston (pL).
Since
Ex. Assume on the hydraulic press shown a 220 N
force is applied to the small piston of surface
0.12 m2. If the surface area of the large piston is
3.0 m2, what total force is exerted?
Pascal’s law is the basis for the hydraulic brake.
When the brake is pushed, the pressure on
the brake fluid in the master cylinder is
increased.
This pressure is transmitted through the fluid
to 8 other cylinders, 2 on each wheel.
The increased pressure on the brake pads
exerts a frictional resistance on the wheel
disks, slowing down the car.