Question 7: A spherical body is dropped in two different fluids and the terminal velocity is found to be different. Give the reason.
We know that the terminal velocity of a spherical body in a fluid of viscosity η is given by,
Now for a particular body, the term is constant. So,
Hence, terminal velocity is inversely proportional to the viscosity of the fluid in which the body moves.
Since viscosity of different fluids are different from one another, therefore, the terminal velocities are also different in different fluids.
So, the spherical body in the given problem would have different terminal velocities in the two fluids because of the different viscosities of the two fluids.