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Pascal's Law - Practice Questions & MCQ

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

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• 12 Questions around this concept.

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Given below are two statements: one is labeled as Assertion A and the other is labeled as Reason R
Assertion A: When you squeeze one end of a tube to get toothpaste out from the other end. Pascal's principle is observed.
Reason R: A change in the pressure applied to an enclosed incompressible fluid is transmitted undiminished to every portion of the fluid and the walls of its container.

In the light of the above statements, choose the most appropriate answer from the options given below

A hydraulic automobile lift is designed to lift vehicles of mass $5000 \mathrm{~kg}$. The area of cross section of the cylinder carrying the load is $250 \mathrm{~cm}^{2}$. The maximum pressure the smaller piston would have to bear is $[Assume \left.g=10 \mathrm{~m} / \mathrm{s}^{2}\right]$:

A piston of a cross-sectional area of 100 cm2 is used in a hydraulic pressure that exerts a force of 107 dynes on the water. The cross-sectional area of the other piston which supports a truck of mass 2000 kg is :

The liquid is filled in a cylindrical container of radius R. What should be the height of the liquid, so that force at the wal of the container equal to force at the bottom

Concepts Covered - 1

Pascal's law

Pascal's law states that if gravity effect is neglected then the pressure at a point in a fluid at rest is the same in all directions.

This law helps us to understand the isotropic nature of pressure.

Pascal's law can be also stated as

The increase in pressure at one point of the enclosed liquid in the equilibrium of rest is transmitted equally to all other points of the liquid and also to the walls of the container, provided the effect of gravity is neglected.

The applications of this law can be seen in Hydraulic lift, hydraulic press, and hydraulic brakes, etc

Working of hydraulic lift-

A hydraulic lift is used to lift the heavy loads.

For the above figure

If a small force f is applied on the piston of C then the pressure exerted on the liquid

$P=\frac{f}{a}$

Where

a = Area of a cross-section of the piston in C

This pressure is transmitted equally to piston of cylinder D.

So $\frac{f}{a}= \frac{F}{A}\Rightarrow F= \frac{f}{a}A$

Where F=Upward force acting on the piston of cylinder D.

A=Area of a cross-section of the piston in D

Condition of Hydraulic Lift-

$A> > a\: \: therefore$

$F> > f$

So heavy load placed on the larger Piston is easily lifted upward.

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Pascal's law

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Pascal's law

Physics Part II Textbook for Class XI

Page No. : 255

Line : 31