Question

A cylinder of `150 mm` radius rotates concentrically inside a fixed cylinder of `155 mm` radius. Both culinders are `300 mm` long. Determine the viscosity of the liquid which fills the space between the cylinders if a torque of `0.98 n-m` is required to maintain an angular velocity of `60 r.p.m.`

Answer 1

Correct Answer - `eta = 0.77 N-sec//m^(2)`
Stress in wire `B = (mg)/(3pir_(B)^(2))`
Stress in wire `B = (4mg)/(3pir_(A)^(2))`
if `(mg)/(3pir_(B)^(2)) = (4mg)/(3pir_(A)^(2))` either wire will break.