Question

Thin discs with mass M and radius R spin at constant velocity w. Two particles, each with mass m are placed slowly on the edge of the disc (at the diametric position). The speed of the disk angle becomes ..

A. (M w) | (M + m)
B. (M w) | M + m)
C. (M w) | (2M + m)
D. (M w) | (M + 2m)
E. (2m w) | (M + m)

Answer 1

$\displaystyle L=L\\I_1\omega_1=I_2\omega_2\\\frac12Mr^2\omega=\frac{1}{2}(M+2m)r^2\omega_2\\M\omega=(M+2m)\omega_2\\\boxed{\boxed{\frac{M}{M+2m}\omega=\omega_2}}$