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# Variation Of Pressure - Practice Questions & MCQ

Edited By admin | Updated on Sep 18, 2023 18:34 AM | #JEE Main

## Quick Facts

• Variation of pressure is considered one of the most asked concept.

• 31 Questions around this concept.

## Solve by difficulty

A ball is made of a material of density where with representing the densities of oil and water, respectively. The oil and water are immiscible. If the above ball is in equilibrium in a mixture of this oil and water, which of the following pictures represents its equilibrium position?

## Concepts Covered - 1

Variation of pressure

1. Variation of pressure with depth

• Pressure varies with height/depth

Have a look at the below figure

Here P0= Atmospheric pressure at the upper surface

And   h= depth below the  upper surface

$\rho$= density of  liquid

P=Hydrostatic pressure for a point at depth h below the  upper surface

Then P is given by $P= P_{0}+\rho\: gh$

Means Pressure increases with depth linearly.

•        Hydrostatic pressure=Absolute Pressure=$P= P_{0}+\rho\: gh$

Absolute Pressure is always positive, It can never be zero.

From equation $P= P_{0}+\rho\: gh$

We can say that

1. Hydrostatic pressure depends on

• h=depth of the point below the surface

• $\rho$=nature of liquid

• g=acceleration due to gravity

1. Hydrostatic pressure does not  depend on

• amount of liquid

• the shape of the container

From this, we can say that for the below figure where the liquid is filled in vessels of

different shapes to the same height,

the pressure at the base in each vessels will be the same, though

the volume or weight of the liquid in different vessels will be different.

I.e In the above figure $P_{A}= P_{B}= P_{C}$

•   Gauge Pressure-  Gauge Pressure is known as the pressure difference between hydrostatic and atmospheric pressure.

So Gauge Pressure is given as $P-P_{0}= gauge \: pressure$

In the equation           $P= P_{0}+\rho\: gh$

The term $\rho gh$  is known as pressure due to liquid column of height h

We can rewrite the above equation as  $\rho\: gh=P-P_{0}$

Or we can say that  Gauge Pressure = $\rho\: gh=P-P_{0}$

It may be positive or negative or zero

1. Variation of pressure along Horizontally

The pressure is uniform on a horizontal line.

For the below figure

In horizontal line or in horizontal plane in stationary liquid

$P_{A}= P_{B}= P_{C}$

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Variation of pressure

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## Books

### Reference Books

#### Variation of pressure

Physics Part II Textbook for Class XI

Page No. : 253

Line : 1