Tag: pressure in fluids

Questions Related to pressure in fluids

The pressure of water on the ground floor is 50000 Pa and at the first floor is 20000 Pa. Find the height of the first floor. Take density of water is $10^3 kg m^{-3}$ and $g=10 ms^{-2}$

physics forces and matter pressure in fluids pressure in liquids introduction to pressure

  1. 2 m

  2. 3 m

  3. 4 m

  4. 5 m

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Correct Option: B
Explanation:

Pressure on the ground floor $=$ Pressure on the first floor + hdg
$\Rightarrow 50000=20000+hdg$
$\Rightarrow 50000=20000+h\times 10^3\times 10$
$\Rightarrow h\times 10^4=50000-20000$
$\Rightarrow h=\frac {30000}{10000}m$
$\Rightarrow height=3 m.$

Calculate the pressure exerted by 0.8 m vertical length of alcohol of density $0.8 g cm^{-3}$. (Acceleration due to gravity $(g)=10 m s^{-2})$.

physics forces and matter pressure in fluids pressure in liquids introduction to pressure

  1. 3200 Pa

  2. 6400 Pa

  3. 800 Pa

  4. 5000 Pa

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Correct Option: B
Explanation:

Vertical length of the alcohol column
$(h)=0.8 m$
Density of alcohol $(d)=0.8 g cm^{-3}$
$=0.8\times 1000=800 kg m^{-3}$
$[\therefore 1 g cm^{-3}=1000 kg m^{-3}]$
$Pressure = hdg$
$=0.8\times 800\times 10$
$=6400 Pa$
Therefore, pressure exerted by the alcohol column is 6400 Pa.

Calculate the pressure exerted by water at the bottom of a lake of depth 6 m. (Density of water $=1000 kg m^{-3}, g=10 ms^{-2})$.

physics forces and matter pressure in fluids pressure in liquids introduction to pressure

  1. $2\times 10^4 Pa$

  2. $4\times 10^4 Pa$

  3. $6\times 10^4 Pa$

  4. $8\times 10^4 Pa$

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Correct Option: C
Explanation:

Height $(h)=6 m$,

$density=1000 kg m^{-3}$,
$g=10 m s^{-2}, Pressure = ?$
$P=hdg$
$=6\times 1000\times 10 Pa$
$=60000 Pa$
$=6\times 10^4 Pa.$

Calculate the vertical height of a mercury column which exerts a pressure of 81600 Pa. (Density of mercury is $13.6 g cm^{-3}$ and $g=10 ms^{-2})$.

physics forces and matter pressure in fluids pressure in liquids introduction to pressure

  1. 0.2 m

  2. 0.4 m

  3. 0.6 m

  4. 0.8 m

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Correct Option: C
Explanation:

$Pressure (P)=81600 Pa$
$Density (d)=13.6 g cm^{-3}$
$=13.6\times 1000 kg m^{-3}$
$(\therefore 1 g cm^{-3}=1000 kg m^{-3})$

Acceleration due to gravity $(g)=10 ms^{-2}$
$P=hdg$
$\Rightarrow h=\dfrac {P}{dg}=\dfrac {81600}{13.6\times 1000\times 10}$
$\Rightarrow h=0.6 m$
Therefore, vertical height of mercury column is 0.6 m.

A liquid of density $12 kg m^{-3}$ exerts a pressure of 600 Pa at a point inside a liquid. What is height of liquid column above that point? $[g=10 ms^{-2}]$

physics forces and matter pressure in fluids pressure in liquids introduction to pressure

  1. 4 m

  2. 5 m

  3. 6 m

  4. 7 m

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Correct Option: B
Explanation:

$Denstiy = 12 kg m^{-3}, Pressure=600 Pa$
$Pressure=hdg$
$\Rightarrow hdg=Pressure\Rightarrow height=\dfrac {P}{dg}$
$=\dfrac {600}{12\times 10}m=5m.$

A metal cube is placed in an empty vessel. When water is filled in the vessel so that  cube is completely immersed in the water, the force on the bottom of the vessel in contact with the cube-

physics forces and matter pressure in fluids pressure in liquids introduction to pressure

  1. Will increase

  2. Will decrease

  3. Will remain the same

  4. Will become zero

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Correct Option: C

Standing liquid exerts pressure on the bottom due to its:

physics forces and matter pressure in fluids pressure in liquids introduction to pressure

  1. mass

  2. weight

  3. both mass and weight

  4. none of these

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Correct Option: C
Explanation:

Every liquid has a density and volume which implies that it has mass & all the bodies having under gravity exerts weight.

A tank filled with water is placed in vacuum. The net pressure at point which is $10 m$ below the surface of water will be $(g = 10 m/s^2)$

physics forces and matter pressure in fluids pressure in liquids introduction to pressure

  1. $100 \ kPa$

  2. $10 \ kPa$

  3. $1 \ kPa$

  4. Zero

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Correct Option: B
A fluid exert pressure 
physics forces and matter pressure in fluids pressure in liquids introduction to pressure

  1. only downwards

  2. only upwards

  3. in all directions

  4. Fluids do not exert pressure

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Correct Option: C
Explanation:

A fluid is a substance that has no fixed shape and yields easily to external pressure; a gas or  a liquid.

Pressure is exerted by fluids because of their weight. Static fluid pressure is exerted by the depth of the fluid, the density of the fluid and the acceleration of gravity. They exert pressure in all directions, which is given by $F=PA$
where $P$ is the pressure, and $A$ is the area on which force acts.

Which of the following can exert pressure
physics forces and matter pressure in fluids pressure in liquids introduction to pressure

  1. Solids

  2. Liquids

  3. Gases

  4. All of the above

Show answer
Correct Option: D
Explanation:

A fluid is a substance that has no fixed shape and yields easily to external pressure; a gas or  a liquid.

Pressure is exerted by fluids because of their weight. Static fluid pressure is exerted by the depth of the fluid, the density of the fluid and the acceleration of gravity.
Well knowingly, the solids exert pressure on the surface on which they are placed, given by $P=\dfrac{mg}{A}$
Hence correct answer is option D.