Tag: physics

Questions Related to physics

A tank $5\ m$ high is half filled with water and then is filled to the top with oil of density $0.85\ g\ cm^{-3}$. The pressure at the bottom of the tank, due to these liquids, is

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

  1. $1.85\ g$

  2. $89.25\ g\ dyne\ cm^{-3}$

  3. $462.5\ g\ dyne\ cm^{-2}$

  4. $500\ g\ dyne\ cm^{-2}$

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Correct Option: C
Explanation:

We know that the pressure increases as we go deep into a liquid. The relation is given by $\Delta P = \rho g\Delta h$


Given that the tank is half filled with water and half with oil.
Thus, $h _\textrm{oil} = 2.5\textrm{ m}$ and $h _\textrm{water} = 2.5\textrm{ m}$

Thus, pressure at the bottom of the tank is $\Delta P = \Delta P _\textrm{oil} + \Delta P _\textrm{water} = 0.85\times 250g + 1\times 250g=462.5g \textrm{ dyne cm}^{-2}$

A barometer which measures atmospheric pressure more accurately is ..........

physics fluids pressure in fluids pressure in liquids introduction to pressure

  1. Fortin's barometer

  2. mercury barometer

  3. anaeroid barometer

  4. Torricelli barometer

Show answer
Correct Option: B
Explanation:

A barometer which measures atmospheric pressure most accurately is mercury barometer.

Hence, option B is correct.

The Pressure at any point in the liquid is proportional to :

physics pressure pressure in fluids pressure in liquids introduction to pressure

  1. The density of liquid.

  2. The depth of point below the surface.

  3. The acceleration due to gravity.

  4. All the above

Show answer
Correct Option: D
Explanation:

Pressure at any point in the liquid $(P)=hdg$
i.e., $P\alpha h$
(depth of point below the surface)
$\alpha d$ (density of liquid)
$\alpha g$ (acceleration due to gravity)

Liquid pressure at a point in a liquid does not depend on the :

physics pressure pressure in fluids pressure in liquids introduction to pressure

  1. Density of liquid

  2. Shape of the vessel in which the liquid is kept

  3. Depth of the point from the surface

  4. Acceleration due to gravity

Show answer
Correct Option: B
Explanation:

pressure in a fluid = $\rho gh $ 

so clearly it is independent of the shape of the vessel in which the liquid is kept .
hence option (B) is correct .

Which of the following scientists invented mercury barometer?

physics fluids pressure in fluids pressure in liquids introduction to pressure

  1. Blaise Pascal

  2. Evangelist Torricelli

  3. Robert Brown

  4. Amedeo Avogadro

Show answer
Correct Option: B
Explanation:

Mercury Barometer was invented by Evangelist Torricelli in the year 1643. It is a device used to measure atmospheric pressure.

A fluid exerts pressure in all possible directions of a container.

physics fluids pressure in fluids pressure in liquids introduction to pressure

  1. True

  2. False

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Correct Option: A
Explanation:

this is the property of fluid to exert pressure in all directions of a container.

so option (A) is correct

Pressure at a point inside the liquid does not depend upon :

physics fluids pressure in fluids pressure in liquids introduction to pressure

  1. The depth of the point below the surface of the liquid.

  2. The nature of the liquid.

  3. The acceleration due to gravity at that point.

  4. The shape of the container.

Show answer
Correct Option: D
Explanation:

Pressure at a point inside the liquid $(P)=hdg$
Hence, it depends on the depth of the point below the surface of the liquid the acceleration due to gravity at that point and on the nature of the liquid but not on the shape of the containing liquid.

Extremely small pollen grains in water are viewed through a microscope. The grains are seen to
move continually and randomly.
What is the reason for this random movement?

physics pressure pressure in fluids pressure in liquids introduction to pressure

  1. The grains are moved by randomly moving water molecules

  2. The grains are moved by random convection currents in the water

  3. The grains are moved by random rays of light reflecting off them

  4. The grains are moved by the random motion of their own atoms

Show answer
Correct Option: A
Explanation:

This is due to brownian motion of fluid particles. The pollen get hitted by the water molecules and carried away by them. 

This is reason behind the random motion of pollen grains in water .

A hose shoots water straight up to a height of $2.5m$. The opening end of the hose an area of $0.75\ cm^{2}$. How much water will come out in one minute ?

physics pressure pressure in fluids pressure in liquids introduction to pressure

  1. $21.5\ litre$

  2. $25\ litre$

  3. $30\ litre$

  4. $31.5\ litre$

Show answer
Correct Option: A

The deep sea divers wear specially designed suites to protect from

physics pressure pressure in fluids pressure in liquids introduction to pressure

  1. different sea organisms

  2. different sea plants

  3. high water pressure

  4. none

Show answer
Correct Option: C
Explanation:

To be able to bear very high pressure of liquid in deep sea.