Question

Explain terminal velocity

Answer 1

Terminal velocity is the constant maximum speed that a body acquires when falling through a fluid. This maximum speed is achieved when the net force acting on the body becomes zero. At this point, the downward gravitational force (weight) is exactly balanced by the sum of the upward buoyant force and the upward viscous drag force exerted by the fluid. Since the net force on the body is zero, its acceleration is zero ($a = F_{net}/m = 0$), and it continues to move at this constant velocity, known as terminal velocity.

Answer 2

A falling object experiences three primary forces: gravitational force pulling it down, and buoyant and viscous drag forces pushing it up. At terminal velocity, these forces are in equilibrium. For a spherical object of radius $r$, density $\rho_0$, falling through a fluid of density $\rho$ and viscosity $\eta$, the terminal velocity ($v$) is given by Stoke's Law: $v = \dfrac{{2{r^2}\left( {{\rho _0} - \rho } \right)g}}{{9\eta }}$ This formula indicates that terminal velocity depends on the square of the object's radius ($r^2$), the difference between the object's density and the fluid's density ($\rho_0 - \rho$), the acceleration due to gravity ($g$), and the viscosity of the fluid ($\eta$).