6.9 Pascal's Law

6.9 Pascal's Law

When we inflate a balloon, we blow air into it with a certain pressure, but the balloon blows uniformly from all sides. It means that the pressure applied at its mouth has been transmitted uniformly in all directions. Similarly, when a motorbike tyre is inflated, air pressure is applied at one point but the tyre is uniformly inflated from all sides. This indicates that pressure is transmitted to each part of the tyre.

Let us consider a liquid. If we push a piston through some distance in a flask containing water with side tubes, the level of water in all the side tubes rises to the same height. This is because the pressure applied at one point of the liquid is transmitted equally to every point of the liquid. Since gases and liquids are termed fluids, this proves that:

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When pressure is applied at one point in an enclosed fluid, it is transmitted equally to all parts of the fluid without loss.

This is the statement of Pascal's law.

The technology of hydraulic systems is based on Pascal's law. Its main advantages are:

1. Liquids do not absorb any of the supplied energy.
2. They are capable of moving heavy loads and providing great forces due to incompressibility.

Some useful hydraulic systems are:

1. Hydraulic press
2. Car lift at service stations
3. Hydraulic brakes of vehicles