Question

A fidget spinner of radius R=0.05m has a moment of inertia l=1.25 x 10^-4 kg m^2 and is rotating at 8.40 rad/s. A large fly whose mass is 0.3 kg lands onto the edge of the rotating spinner. Calculate the angular speed of the system after the fly falling onto the spinner.

Answer 1

$I_0\omega_0=(I_0+mr^2)\omega\to$

$\omega=I_0\omega_0/(I_0+mr^2)=1.25\cdot10^{-4}\cdot8.4/(1.25\cdot10^{-4}+0.3\cdot0.05^2)=1.2\ (rad/s)$