Home
Class 11
PHYSICS
A space 2.5cm wide between two large pla...


A space `2.5cm` wide between two large plane surfaces is filled with oil. Force required to drag a very thin plate of area `0.5m^2` just midway the surfaces at a speed of `0.5(m)/(sec)` is `1N`. The coefficient of viscosity in `kg-(s)/(m^2)` is:

A

`5xx10^(-2)`

B

`2.5 xx10^(-2)`

C

`1xx10^(-2)`

D

`7.5 xx10^(-2)`

Text Solution

Verified by Experts

The correct Answer is:
B
Velocity gradient `=0.5/(2.5/2xx10^(-2))`
as force on the plate due to viscocity is from upper as well as lower portion of the oil, equal from each part,
Then`F=2 etaA(dv)/(dz) =2xxetaxx(0.5)0.5/(1.25xx10^(-2))`

`rArr eta=2.5xx10^(-2) kg -sec//m^(2)`
Promotional Banner

Topper's Solved these Questions

  • FLUID MECHANICS

    RESONANCE|Exercise Examples|22 Videos

  • FLUID MECHANICS

    RESONANCE|Exercise Board Level Exercise|18 Videos

  • ELECTROSTATICS

    RESONANCE|Exercise Exercise|52 Videos

  • FULL TEST 1

    RESONANCE|Exercise Exercise|30 Videos

Similar Questions

Explore conceptually related problems

The force of 2000 dyne is required to move a flat glass plate of surface area 10 cm^(2) with a velocity of 1 cm/s over a surface of glycerine 1 mm thick. The coefficient of viscosity of glycerine is

A force of 3.14 N is required to drag a sphere of radius 4 cm with a speed of 5 ms^(-1) in a medium in gravity free space. Find the coefficient of the viscosity of the medium.

Glycerine is filled in 25 mm wide space between two large plane horizontal surfaces. A thin plate of area 0.75 m^(2) at a distance of 10 mm from one of the surfaces is in a horizontal position be the plates inside the glycerine. It is dragged horizontally at a constant speed of 0.5 ms^(2) . Take coefficient of viscosity eta =" 0.5 Ns m"^(-2) . What is the force required to drag the plate at a constant speed (in newton) ?

A metal plate of area 500 cm^92) is kept on a horizontal surface with a layer of oil of thickness 0.5 mm between them. The horizontal force required to drag the plate with a velocity of 2 cm/s is (coefficient of viscosity =0.9 kg/ms)

There is a 1 mm thick layer of oil between a flat plate of area 10^(-2)m^(2) and a big plate. How much force is required to move the plate with a velocity of 1.5 cm//s^ . The coefficient of viscosity of oil is 1 poise

A rectangular metal plate has dimensions of 10cmxx20cm . A thin film of oil separates the plate from a fixed horizontal surface. The separation between the rectangular plate and the horizontal surface is 0.2mm . An ideal string is attached to the plate and passes over an ideal pulley to a mass m . When m=125gm , the metal plate moves at constant speed of 5(cm)/(s) , across the horizontal surface. Then the coefficient of viscosity of oil in (dyne-s)/(cm^2) is (Use g=1000(cm)/(s^2) )

Find the minimum force required to drag a hard polythene plate of area 2 m^(2) on a thin film of oil of thickness 0.25 cm and eta= 15 poise. Assume the speed of the plate is 10 cm s^(-1) .

The surface tension of a liquid is 0.5 N/m . If a liquid film is formed on a ring of area 0.02 m^(2) then its surface energy will be