A small sphere of radius r falls from rest in a viscous liquid. As a result, heat is produced due to viscous force. The rate of production of heat when the sphere attains its terminal velocity, is proportional to

A small sphere of radius r falls from rest in a viscous liquid. As a r

1.	A small sphere of radius r falls from rest in a viscous liquid. As a result, heat is produced due to viscous force. The rate of production of heat when the sphere attains its terminal velocity, is proportional to
Answer» `r^5` `r^2` `r^3` `r^4` Solution :The opposing force due to VISCOSITY , `F =6 PI eta r v` `(DQ)/(dt)=P=F. v=6pi eta r v^2 or,v = kr^2` `therefore P=6pi eta r(kr^2)^2 = 6pi k^2 eta r^5` ` P prop r^5`