Q. 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:
A) Mg
B) $\frac{3}{2}Mg$
C) 2 Mg
D) $\frac{Mg}{2}$
Explanation
[Solution] At terminal velocity, viscous force = weight - buoyancy = Mg - (M/d)(d/2)g = Mg/2. Answer (4).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.