Class 11 Physics Mechanics Mechanical Properties of Fluids
Now the force exerted by the liquid on the plate is:
(a)
0.6 N
(b)
0.4/3 N
(c)
1.6/3N
(d)
None
Solution:

There will be backward viscous force acting on both the sides, first from liquid above the plate, and second from liquid below the plate. In this case for one side liquid is 2 cm and for another side liquid, is 4cm. so we have F_v=\left(\mu
A\dfrac{dv}{dx}\right)_1+\left(\mu A\dfrac{dv}{dx}\right)_2 \\\Rightarrow
F_v= 0.8 \times 0.01 \times \dfrac{1}{0.02} +0.8 \times 0.01 \times
\dfrac{1}{0.04}= 0.6N

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