Q.

A spherical ball of radius 1 mm and density 10.5 g/cc is dropped in glycerine of coefficient of viscosity 9.8 poise and density 1.5 g/cc. The viscous force on the ball when it attains constant velocity is 3696×10-x N. The value of x is. (Given: g=9.8 m/s2 and π=227) ________ .           [2023]


Ans.

(7)

When the ball attains terminal velocity

Fv=(mg-FB)  (a=0)

     =Vσbg-Vρg=V(σb-ρ)

     =43π(10-3)3×9.8(10.5-1.5)×103

      =3696×10-7 N

So, x=7