JEE MAIN - Physics (2004 - No. 40)
Spherical balls of radius $$R$$ are falling in a viscous fluid of viscosity $$\eta $$ with a velocity $$v.$$ The retarding viscous force acting on the spherical ball is
inversely proportional to both radius $$R$$ and velocity $$v$$
directly proportional to both radius $$R$$ and velocity $$v$$
directly proportional to $$R$$ but inversely proportional to $$v$$
inversely proportional to $$R,$$ but directly proportional to velocity $$v$$
Објашњење
From Stoke's law,
viscous force acting on the ball falling into a viscous fluid
$$F = 6\pi \eta Rv$$
$$\therefore$$ $$F \propto R$$ and $$F \propto v$$
hence $$F$$ is directly proportional to radius & velocity.
viscous force acting on the ball falling into a viscous fluid
$$F = 6\pi \eta Rv$$
$$\therefore$$ $$F \propto R$$ and $$F \propto v$$
hence $$F$$ is directly proportional to radius & velocity.