Question

A man is rowing a boat with a constant velocity $v_0$ in a river. The contact area of boat is ‘A’ and co-efficient of viscosity is $\eta$. The depth of river is ‘D’. Find the force required to row the boat.

• A. $2\eta A{v}_{0}D$
• B. $\eta A{v}_{0}D$
• C. $\frac{\eta A{v}_0}{D}$
• D. $\frac{2\eta A{v}_0}{D}$

Answer 1

The correct option is C

$\frac{\eta A{v}_0}{D}$

$F-F_v=MaF=F_v(\because a=0)=\eta A\frac{dv}{dz}F=\frac{\eta A{v}_0}{D}$