NEET Physics Question - Solid and Fluids - Surface Tension and Viscosity

The velocity of a small ball of mass $M$ and density $d$, when dropped in a container filled with glycerine becomes constant after some time. If the density of glycerine is $\frac{d}{2}$, then the viscous force acting on the ball will be:

(2021)

$Mg$

$\frac{3}{2}Mg$

$2Mg$

$\frac{Mg}{2}$

Solution:

At constant terminal velocity, net force is zero. Viscous force $F_v = \text{Weight} - \text{Buoyant force}$. $$F_v = Vdg - V\left(\frac{d}{2}\right)g = \frac{Vdg}{2} = \frac{Mg}{2}$$.

Rankers Physics

Solution:

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