There is a $1$ $mm $ thick layer of glycerine between a flat plate of area $100$ $cm^2$ $\&$ a big fixed plate. If the coefficient of viscosity of glycerine is $1.0$ $kg/m^{-s}$ then ....... $N$ force is required to move the plate with a velocity of $7$ $cm/s$ ?
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Using the relation $\tau=\frac{F}{A}=\mu \frac{d u}{d y}$
where $F=$ force is required to move the plate
$\tau=$ Shear stress
$A=$ Area of plate
$\mu=$ coeffecient of viscosity of glycerine
$y=g a p$
$\mathrm{u}=$ velocity
$\frac{F}{10^{-2}}=1 \times \frac{0.07}{0.001}$
Thus $F=0.7 \mathrm{N}$
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