Tag: fluid pressure

Questions Related to fluid pressure

When the volume of gas is reduced at constant temperature, the pressure exerted by the gas on the walls of the container increases because

physics option b: engineering physics buoyancy floatation fluid pressure

  1. each molecules hits the walls with greater speed

  2. each molecule loses more energy when it strikes the wall

  3. each molecule loses momentum when it strikes the wall

  4. the number of molecules striking the wall per unit time increase.

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Correct Option: C

A container with insulating walls is divided into equal parts by a partition fitted with a value.One part is filled with an ideal gas at a pressure P and temperature T, whereas the other part is completely evacuted.If the value is suddenly opened,the pressure and temperature of the gas will be

physics option b: engineering physics buoyancy floatation fluid pressure

  1. $ \dfrac {p}{2}, T $

  2. $ \dfrac {p}{2} , \frac {T}{2} $

  3. p,T

  4. $ p, \dfrac {T}{2}, $

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Correct Option: A

A cylindrical vessel of $100\ cm$ height is kept filled upto the brim. It has four holes $1, 2, 3, 4$ which are respectively at heights of $27\ cm, 30\ cm, 50\ cm$ and $80\ cm$ from the horizontal floor. The water falling at the maximum horizontal distance from the vessel comes from

physics option b: engineering physics buoyancy floatation fluid pressure

  1. Hole number $4$

  2. Hole number $3$

  3. Hole number $2$

  4. Hole number $1$

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Correct Option: C

Water is falling in a cylindrical tank at the rate of $ \pi m^3 / s. $ If the radius of the tank is 2 m, the rate of increases in the level of water in the tank is

physics option b: engineering physics buoyancy floatation fluid pressure

  1. 1 m/s

  2. 0.25 m/s

  3. 0.5 m/s

  4. none

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Correct Option: C

The pressure and temperature of an ideal gas in a closed vessel are $720$ kpa and $40^oC$ respectively. If - th of the gas is released from the vessel and the temperature of the remaining gas is raised to $353^oC$, the final pressure of the gas is 

physics option b: engineering physics buoyancy floatation fluid pressure

  1. $ 1440$ kPa

  2. $1080$ kPa

  3. $720$ kPa

  4. $ 540$ kPa

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Correct Option: B

Two metal plates $'A'$ and $'B'$ having the same breadth but different lengths $\ell 1$ and $\ell _2 $ respectively are placed at same depth inside water such that their breadth is held exactly in vertical positions. Then, the ratio of the pressure acting on $'A'$ and $'B'$ by water is ____.

physics option b: engineering physics buoyancy floatation fluid pressure

  1. $1:1$

  2. $\ell _1:\ell _2$

  3. $\ell _2:\ell _1$

  4. $\ell _1 b:\frac{\ell _2}{b}$

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Correct Option: C

The water flowing from a garden hose fills a container $ 3 \pi $ litre in one minute.Then speed of the water coming from that pipe with opening of radius 1 cm is 

physics option b: engineering physics buoyancy floatation fluid pressure

  1. $ 4 ms^{-1} $

  2. $5 ms^{-1} $

  3. $ 1 ms^{-1} $

  4. $ 0.5 ms^{-1} $

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Correct Option: A

A container holds $ 10^{26} molecules / m^3 $ each of mass $ 3 \times 10^{-27} $ Kg. Assume that 1/6 of the ,molecule move with  velocity 2000 m/s directly towards one wall of the container while the remaining 5/6 of the molecules move either away from the wall or in perpendicular direction, and all collision of the molecules with the wall or in perpendicular direction, and all collision of the molecules with the wall are elastic.

physics option b: engineering physics buoyancy floatation fluid pressure

  1. Number of molecules hitting $ 1 m^2 $ of the wall every second is $ 3 .33 \times 10^{28} $

  2. Number of molecules hitting $ 1 m^2 $ of the wall every second is $ 2 \times 10^{29} $

  3. Pressure exerted on the wall by molecules is $ 24 \times 10^5 Pa. $

  4. Pressure exerted on the wall by moleculaes is $ 4 \times 10^5 Pa, $

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Correct Option: C

To what height h should a cylindrical vessel of diameter d be filled with a liquid so that the total force on the vertical surface of the vessel be equal to the force on the bottom-

physics option b: engineering physics buoyancy floatation fluid pressure

  1. $h=d$

  2. $h=2d$

  3. $h=3d$

  4. $h=d/2$

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Correct Option: D
Explanation:

If we fill the cylinder upto a height h, the force exerted on at the bottom of the cylinder would be equal to F = PA


$ F = \rho gh \times \pi d^2/4 $

Similarly, the average force exerted along the sides of the cylinder will be because of half the height filled for the cylinder.

Therefore, $ F = \rho g h/2 \times \pi d h $

Equating the 2 forces, and solving for h, gives h = d/2

The height of liquid in a cylindrical vessel of diameter $d$ so that the total force on the vertical surface of the vessel be equal to the force on the bottom, will be:

physics option b: engineering physics buoyancy floatation fluid pressure

  1. $d$

  2. $2d$

  3. $4d$

  4. $\cfrac{d}{2}$

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Correct Option: D