Tag: fluid pressure

Questions Related to fluid pressure

The temperature of an air bubble while rising from bottom to surface of a lake remains constant but its diameter is doubled if the pressure on the surface is equal to h meter of mercury column and relative density of mercury is p then the depth of lake in metre is

physics fluid pressure pressure in air introduction to atmospheric pressure pressure exerted by air devices to measure pressure

  1. $2\rho h$

  2. $4\rho h$

  3. $8\rho h$

  4. $7\rho h$

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Correct Option: D

The pressure of water at bottom in a lake is 3/2 times that at half depth where the water barometer reads $10$ m. The depth of the lake is:

physics fluid pressure pressure in air introduction to atmospheric pressure pressure exerted by air devices to measure pressure

  1. $15$ m

  2. infinite

  3. $20$ m

  4. $10$ m

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Correct Option: C
Explanation:

Let the point at half depth be $x,$

$P _1=P+dgx$

Let the depth of lake be $2x$,

$P _2=P+dg2x$

$P _2=3/2×P1$

$2P _2=3P1$

$2 (P+dg2x)=3 (P+dgx)$

$2P+4dgx=3P + 3dgx$

$P=dgx$

$x=P/dg$

$x=10^5/10000 (d=10^3kg/m^3) (P=10^5pa)$

But depth of lake is $2x$

$2x=2×10=20m$

Two communicating vessels contain mercury. The diameter of one vessel is four times larger than the diameter of the other. A column of water of height $h _0=70$ cm is poured into the left hand vessel (the narrower one). How much will be mercury level rise in the right hand vessel? ( Specific density of mercury= $13.6$)

physics fluid pressure pressure in air introduction to atmospheric pressure pressure exerted by air devices to measure pressure

  1. $0.3$ cm

  2. $0.7$ cm

  3. $0.1$ cm

  4. $1.0$ cm

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Correct Option: D

The height of mercury $(h)$ in the manometer is

physics fluid pressure pressure in air introduction to atmospheric pressure pressure exerted by air devices to measure pressure

  1. $760\ mm$

  2. $172\ mm$

  3. $272\ mm$

  4. $300\ mm$

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Correct Option: D
Explanation:
The height of mercury (h) in the manometer is $0.30 m$
Hence,
Option $D$ is correct answer.

8 gm $O _{2}$,14 gm $N _{2}$ and 22 gm $CO _{2}$ is mixed in a container of 10 litre capacity at $27^oC$.The pressure exerted by the mixture in terms of atmospheric pressure will be-

physics fluid pressure pressure in air introduction to atmospheric pressure pressure exerted by air devices to measure pressure

  1. 1

  2. 3

  3. 9

  4. 18

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Correct Option: C

Suppose the density of air at Hyderabad is $\rho _ { 0 }$ and atmospheric pressure is $P _ { \mathrm { atm } }$.Suppose we wish to calculate the pressure $P$ at a height $10 \mathrm { km }$ above Hyderabad. If we use the equation $P _ { 0 } - P = \rho g z$ to calculate $P$ with $z = 10 km$. But if we take only variation of $\rho$ with height we get $P _1$. if we take only of $g$ with height we get $P _2$, if we take both $\rho$ and $g$ variations with height we get $P _3$. Then 

physics fluid pressure pressure in air introduction to atmospheric pressure pressure exerted by air devices to measure pressure

  1. $P = P _ { 1 } = P _ { 2 } = P _ { 3 }$

  2. $P _ { 3 } < P _ { 1 }$

  3. $P _ { 2 } > P$

  4. $P _ { 0 } - P > P _ { 0 } - P _ { 3 }$

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Correct Option: C

An air bubble doubles its radius on rising from the bottom of water reservoir to the surface of water in it. If the atmospheric pressure is equal to $10 m $ of water, the height of water in the reservation s- 

physics fluid pressure pressure in air introduction to atmospheric pressure pressure exerted by air devices to measure pressure

  1. $ 10m $

  2. $20 m$

  3. $70 m$

  4. $80 m$

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Correct Option: C

A cubical block of steel each side '$\ell $' is floating in mercury in a vessel. The densities of steel and mercury are ${ p } _{ s }\quad and\quad { p } _{ m }$ .The height of block above the mercury level is given by.

physics fluid pressure pressure in air introduction to atmospheric pressure pressure exerted by air devices to measure pressure

  1. $\ell \left( 1+\dfrac { { p } _{ s } }{ { p } _{ m } } \right) $

  2. $\ell \left( 1-\dfrac { { p } _{ s } }{ { p } _{ m } } \right) $

  3. $\ell \left( 1+\dfrac { { p } _{ m } }{ { p } _{ s } } \right) $

  4. $\ell \left( 1-\dfrac { { p } _{ m } }{ { p } _{ s } } \right) $

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Correct Option: B

A flask of volume $10^3cc$ is completely filled with mercury at $0^oC.$ The co-efficient of cubical expansion of mercury is $180\times10^{-6} /^oC$ at that of glass is $40\times10^{-6}/^oC.$ If flask is placed in boiling water at $100^oC,$ how much mercury will overflow   

physics fluid pressure pressure in air introduction to atmospheric pressure pressure exerted by air devices to measure pressure

  1. $7cc$

  2. $14cc$

  3. $21cc$

  4. $28cc$

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Correct Option: B

Positive and negative ions are produced in the atmosphere due to cosmic rays from space and also due to radioactive element in the soil . in some region in the atmosphere the electric field strength is 100 V/m in the vertically downwaeds direction. This field exerts force on the positive and negative ions in the given region in atmosphere . as a result, positive ions , having a density $ 500/cm^3 $ drift downward while negative ions , havig a density $ 300/cm^3 $ drift upward al these ions are singly charged. it is observed that the conductivity in the given region is $ 4 \times 10^{-13} $ $ (\Omega -m)^{-1} $ . find the average speed of ions, assuming it to be the same for positive and negative ions.

physics fluid pressure pressure in air introduction to atmospheric pressure pressure exerted by air devices to measure pressure

  1. $1.3 m/s$

  2. $0.31 m/s$

  3. $0.93 m/s$

  4. $1.6 m/s$

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Correct Option: D