Question

Two masses $M$ and $m$ are attached to a vertical axis by weightless thread of combined length $l.$ They are set in rotational motion in a horizontal plane about this axis with constant angular velocity $\omega$ . If the tensions in the thread are same during motion, the distance of M from the axis is,

• A. $\frac{Ml}{M+m}$
• B. $\frac{ml}{M+m}$
• C. $\frac{M+m}{M}l$
• D. $\frac{M+m}{m}l$

Answer 1

Answer: (B)

$\frac{ml}{M+m}$

Answer 2

$m r \omega^{2}=M R \omega^{2}$ Put $r=l-R$ $\therefore m(l-R)=M R$ $\Rightarrow R=\frac{m l}{M +m}$