Viscous Force on Falling Ball – Rankers Physics
Topic: Solid and Fluids
Subtopic: Surface Tension and Viscosity

Viscous Force on Falling Ball

The velocity of a small ball of mass \(m\) and density \(d\), when dropped in a container filled with glycerine becomes constant after sometime. If the density of glycerine is \(\frac{d}{2}\), then the viscous force acting on the ball will be
\(2mg\)
\(\frac{mg}{2}\)
\(mg\)
\(\frac{3}{2}mg\)

Solution:

At terminal velocity, net force is zero: \(F_v + F_B = mg\). Here, buoyant force \(F_B = V\left(\frac{d}{2}\right)g = \frac{mg}{2}\). Thus, the viscous force is \(F_v = mg - \frac{mg}{2} = \frac{mg}{2}\).

Leave a Reply

Your email address will not be published. Required fields are marked *