The velocity of water in a river is $18 \mathrm{km} {\mathrm{h}}^{-1}$ near the surface. If the river is $5 \mathrm{m}$ deep, find the shearing stress between the horizontal layers of water. The coefficient of viscosity of water$={10}^{-2} \mathrm{poise}$.

• A

  ${10}^{-4} \mathrm{N} {\mathrm{m}}^{-2}$
• Correct answer
  B

  ${10}^{-3} \mathrm{N} {\mathrm{m}}^{-2}$
• C

  ${10}^{-2} \mathrm{N} {\mathrm{m}}^{-2}$
• D

  ${10}^{-1} \mathrm{N} {\mathrm{m}}^{-2}$

Hence, the correct answer is option: 'B'.