Question

What is SI unit of viscosity coefficient $\left(\eta \right)$?

(a) Pascal (b) $Ns{m}^{-2}$ (c) $k{m}^{-2}s$ (d) $N{m}^{-2}$

Answer 1

Answer: (b) $Ns{m}^{-2}$

The SI unit of viscosity coefficient $\left(\eta \right)$? is $N{m}^{-2}$ or $Ns{m}^{-2}$.

As we know that, $f=\eta A\frac{dv}{dx}f=force\eta =viscositycoefficient\frac{dv}{dx}=velocitygradient$

Substitute SI units of f=N, dx=m, $A=m^2$ and $v=m{s}^{-1}$

In above equation, to get,

$eta=\frac{N\times m}{m^2\times m{s}^{-2}}=N{m}^{-2}s$

Hence, the si unit of $\eta isNs{m}^{-2}$