PRESSURE

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INTRODUCTIONa)Atmospheric pressureb)b) Fluid pressure

APPLICATION OF PRESSURE

REVISE AND EXPERIMENT

Effect of force on a given area is called pressure.Pressure depends on two factors. They are: force

applied and area over which force acts.The formula of pressure is:

Pressure=Force/Area.

01. INTRODUCTION

Pressure can also be defined in terms of another force called thrust.

The force acting on a body perpendicular to its surface is called thrust.

So, we can also define pressure as thrust per unit area is Pressure=Thrust/Area.

The SI unit of pressure is Pascal (Pa).

“The same force produces less pressure if it acts on a large area but can produce less pressure if

it acts on a small area.”

REMEMBER:

Like all gases, air also have weight hence exerts pressure.

The force exerted by the atmosphere on unit area is called atmospheric pressure.

Air exerts huge pressure in every direction.

( show video about air pressure )

a) Atmospheric pressure

Unlike solids, the liquids do not have a definite shape. They take the shape of the containing vessels.

The pressure in liquids is not thrust per unit area. instead it depends it depends upon the depth and density of the liquid.

Fluids have weight so they exert pressure on the base and walls of the container.

b) Fluid pressure

The pressure at a depth in a liquid depends on two factors:oThe height of the liquid column.oThe density of the liquid.

a. The edge of the knife is made sharper increase pressure.

02. APPLICATION

b. In vacuum cleaner a low pressure is created inside with the help of a fan and this low pressure helps in the working of vacuum cleaner

c. The straw helps us to drink juice because the atmospheric pressure is exerted on the surface of the juice.

The effect of force on a given area is called pressure.

The SI unit of pressure is Pascal(Pa) equal to 1 Newton per meter square the pressure exerted by air is called atmospheric pressure.

Atmospheric pressure is the force exerted by the atmosphere on unit area

A liquid exerts pressure in all direction.

At the same depth the pressure is same in all direction.

Liquid pressure increases with depth

03. REVISION