Question

A metal block of base area $0.20m^2$ is placed on a table, as shown in figure. A liquid film of thickness $0.25mm$ is inserted between the block and the table. The block is pushed by a horizontal force of $0.1N$ and moves with a constant speed. If the viscosity of the liquid is $5.0\times 10^{-3}Pl$, the speed of block is ____$\times 10^{-3}m/s$

Answer 1

Answer: 25

$|F|=\eta A\frac{\Delta v}{\Delta h}:0.1$
$=5\times 10^{-3}\times 0.2\times \frac{v}{.25\times 10^{-3}}$
$v=0.025m/s$
or $v=25\times 10^{-3}m/s$