Physics - Fluid Question with Solution | TestHub

When the velocity of the ball becomes constant, the net force acting on it is zero.

The forces acting on the ball are its weight $W$ downwards, buoyant force $F_B$ upwards, and viscous force $F_V$ upwards.

$W=F_B+F_V$

$F_V=W-F_B$

The volume of the ball is $V=\frac{M}{d}$.

The buoyant force is given by the weight of the displaced liquid:

$F_B=V\times \text{density of glycerine}\times g$

$F_B=\frac{M}{d}\times \frac{d}{2}\times g=\frac{Mg}{2}$

Substituting the values, we get:

$F_V=Mg-\frac{Mg}{2}=\frac{Mg}{2}$

Answer: $\frac{Mg}{2}$