STD IX – FLUIDS – (Online)

PRESSURE IN FLUIDS AND ATMOSPHERIC PRESSURE

Pressure in Fluids and its Transmission

It is important to understand the term thrust first before understanding pressure. The force acting on a surface is known as the thrust. It has both direction and magnitude.

The force exerted per unit area applied in a perpendicular direction to the object surface is known as pressure. This perpendicular force is known as thrust.

Hence, pressure can also be defined as thrust per unit surface area. Fluid pressure is the pressure exerted by a fluid. For example, water (fluid) in a glass (container) exerts pressure in all directions, at all points.

Let’s now define atmospheric pressure. The air in the earth’s atmosphere exerts a force upon all the objects in the atmosphere and also on the earth. Atmospheric pressure can be defined as, the force exerted by the atmospheric air upon a unit area.

UPTHRUST IN FLUIDS AND ARCHIMEDES’ PRINCIPLE

Fluid Pressure:

Pascal’s law: Pressure exerted anywhere in a confined liquid is transmitted equally in all directions.

ATMOSPHERIC PRESSURE

Atmospheric pressure is the force per unit area exerted against a surface by the weight of the air.