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  • Gravitational force
    • Law of gravitation
    • Acceleration(g)
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    • Def.Pressure
    • Principles
    • Upthrust
    • Numerical Problems
  • Heat
    • Heat Energy
    • Anomalous expansion of water
    • Specific heat capacity
    • Numerical Problems
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    • Electricity
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  • Wave Motion

Pascal's Law

Pascals Law Definition: Pressure applied to liquid enclosed in vessel is transmitted equaly all direction perpendicularly. Instruement based on Pascal's Law are Hydraulic lift Hydraulic break Hydraulic Press (Jyak) In right side, all these picture based on Pascal's Law. By the formula P1 = P 2 $\frac{\mathrm{F<sub>\; 1</sub>}}{\mathrm{A\; <sub>1</sub>}}$ = $\frac{\mathrm{F<sub>\; 2</sub>}}{\mathrm{A\; <sub>\; 2\; </sub>}}$

Q. In Pascal's Law based instruements, liquid is used, why?
Q. Pascal's Law based on liquid best not on other, why?

→ Following are the reson why liquid is used.
• Liquid is not compressable
• Liquid can flows all direction and give pressure equally

Q. Driver can stopped heavy truck or bus with minimum force, how? → Hydraulic break is used in bus or truck. Driver use force on small piston and this force is magnifed by large piston which make stop to bus or truck easly.

Archimidies Principle
Definition: "The object partially of fully sink in liquid experience upthrust equal to weight of displaced liquid", this is called Archimides Principle.
→ i.e upthrust = weight of displaced liquid,
→ This principle is also applicable to gas.
Plawan's Law
Definition: "Floating objects displace liquid equal to its weight," is called Plawan's Law.
→ This is applicable to only partially sink object (i.e. floating objects) it can be said that Plawan's law is special case of Archimede's Principle.

Difference between Archimedes and Plawan's Principle
Archimedes Principle	Plawan Principle
1. Upthrust by liquid = displaced liquid weight	1. Weight of floating object = weight of displaced liquid
2. This law is applicable to object which are totally or partially sink.	2. This law is applicable to object which are floating
3. Upthrust based on density of liquid.	3. Upthrust based on weight of object

→ Instruement based on Plawan's Principle
• Hydrometer
• Ship

Hydrometer
Definition: Density measuring instrument of liquid is called, Hydrometer. It is based on Plawan's Principle.
→ Lactometer is a Hydrometer which is used to measure density of milk.
Q. Bulb of Hydrometer is made heavy, why?
→ To stand up vertically, the bulb of Hydrometer is made heavy.
Q. The stem of hydrometer is marked from top to bottom not uniformly gradualed, give reason.
→ As the dinsity of liquid increases, Hydrometer move to upward to measure high density so it is calibrated from higher to lower point.

Substances(Liquid)	Density(gm/cm3)
A	11
B	13.6
C	1
D	0.9
Among the substances A,B,C and D; which substance floats on water, why? → Among these substance 'D' floats on water because its density is less than the water Among the given substances, name the substance that gives greatest upthrust. Give reason also. → As the upthrust is directly proportional to density, among these substance, 'B' gives greatest upthrust because of its maximum density.

Numerical Problem Q. An iceberg (50cm, 30cm,20cm) is put on water. How much fraction it will inside and outside of water? (density of ice is 0.9 gm/cm³ and density of water is 1 gm/cm³)
→ Density of ice d₁ = 0.9 gm/cm³
Density of water d₂ = 1 gm/cm³
Fraction of iceberg inside water = $\frac{\mathrm{d₁}}{\mathrm{d₂}}$
= $\frac{\mathrm{0.9}}{1}$ =$\frac{9}{\mathrm{10}}$ Fraction of iceberg outside water = 1- $\frac{\mathrm{d₁}}{\mathrm{d₂}}$
= 1 - $\frac{9}{\mathrm{10}}$ = $\frac{1}{\mathrm{10}}$