Tag: pressure in air

Questions Related to pressure in air

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

An air tight container having a lid with negligible mass and a area of $8 c m^{2}$ is partially evacuated . If a 40N force is require to pull a lid off the container and the atmospheric pressure is $ 1.0 \times 10^{5} \mathrm{Ps}$ ,the presure in the container before it is opened must be

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

  1. 0.6atm

  2. 0.5atm

  3. 0.4atn

  4. 0.2atm

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Correct Option: C
Explanation:
The pressure inside the container must be equal to the pressure developed by force applied and the atmospheric force would oppose the pull,

So,

$P _{external}=P _{inside}+P _{atmosphere}$

$=\dfrac{48}{0.008}=P _{inside}+1\times 10^5$

$P _{inside}=0.6\times 10^5-1\times 10^5$

$P _{inside}=-0.4\times 10^5\,Ps=0.4\,atm$

What should be the minimum volume of the room, if no liquid water is be  present finally in the room ? 

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

  1. 166.671

  2. 16.671

  3. 166.67 $m^{3}$

  4. 16.67 $m^{3}$

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Correct Option: D

A gas is collected over the water at $25 ^ { \circ } \mathrm { C }$ . The total pressureof moist gas was 735$\mathrm { mm }$ of mercury. If the aqueous vapourpressure at $25 ^ { \circ } \mathrm { C }$ is 23.8$\mathrm { mm }$ . Then the pressure of dry gas is

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

  1. $760$ $\mathrm { mm }$

  2. $758.8$ $\mathrm { mm }$

  3. $710.8$ $\mathrm { mm }$

  4. $711.2$ $\mathrm { mm }$

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Correct Option: D

20$\mathrm { cm }$ containing mercury and two equal ends containing air at standardatmospheric prossure. If the tube is now turned to a vertical position, by what amount will the mercury bo displaced?
(Given : cross-section of the tube can be assumed to be uniform):

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

  1. 2.95$\mathrm { cm }$

  2. 5.18$\mathrm { cm }$

  3. 8.65$\mathrm { cm }$

  4. 0.0$\mathrm { cm }$

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Correct Option: A

The height of mercury column in a simple barometer is h. As the tube is inclined to the vertical at an angle $  \alpha,  $ the length of mercury column along the length of the tube is l; then:

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

  1. $ 1=\frac{h}{\cos \alpha} $

  2. $ 1=h \cos \alpha $

  3. $ I=h $

  4. $ 1=\cos \alpha / h $

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Correct Option: A

A small bulb is filled with air at ${ 41 }^{ 0 }c$ and sealed. When it heated slowly in an oil bath upto ${ 198 }^{ 0 }c$, it is found to be broken. find the pressure at which the bulb is broken.

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

  1. 2.5 atm

  2. 1.5 atm

  3. 3 atm

  4. 1.3 atm

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Correct Option: C

If the intensity of the incident radio wave of  $1\mathrm { w } / \mathrm { w } ^ { 2 }$  is reflected by the surface, find the pressure exerted on the surface?

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

  1. $5.67 \times 10 ^ { - 9 } N / m ^ { 2 }$

  2. $6.67 \times 10 ^ { - 9 } N / m ^ { 2 }$

  3. $8.67 \times 10 ^ { - 9 } N / m ^ { 2 }$

  4. $9.67 \times 10 ^ { - 8 } \mathrm { N } / \mathrm { m } ^ { 2 }$

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Correct Option: B
Explanation:

For reflecting surface, Pressure

$\begin{array}{l} =\frac { { 2F } }{ C }  \ =\frac { { 2\times 1 } }{ { 3\times { { 10 }^{ 8 } } } } =6.67\times { 10^{ -9 } }N/{ m^{ 2 } } \ Ans.\, \, (B) \end{array}$

Which limb of the tube should be connected to the pump?

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

  1. Limb having radius 2 mm

  2. Limb having radius 1 mm

  3. Any of the climb

  4. None of these

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Correct Option: A

A balloon contains  1500 $m^{3}$  of helium at $27^{\circ}C$   and 4 atmoshperic  pressure.  The volume of helium at $3^{\circ}C$  temperature and 2  atmospheric pressure will be 

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

  1. 1500 $m^{3}$

  2. 1700 $m^{3}$

  3. 1900 $m^{3}$

  4. 2700 $m^{3}$

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Correct Option: C