b
Shear force, \(F=T=m g=0.01\; kg \times 10\; m s ^{-2}=0.1\; N\)

Shear stress on the fluid \(=\frac{F}{A}=\frac{0.1\; N }{0.1 \;m ^{2}}\)

Strain rate \(=\frac{v}{l}=\frac{0.085 \;m {s}^{-1}}{0.3 \times 10^{-3}\; m }\)

Coefficient of viscosity, \(\eta=\frac{\text { Shear stress }}{\text { Strain rate }}\)

\(=\left(\frac{0.1\; N }{0.1 \;m ^{2}}\right) \times \frac{\left(0.3 \times 10^{-3}\; m \right)}{0.085\; ms ^{-1}}\)

\(=3.5 \times 10^{-3} Pa\cdot s\)