As shown in the figure, a bob of mass $m$ is tied to a massless string whose other end portion is wound on a fly wheel (disc) of radius $r$ and mass $m$. When released from rest the bob starts falling vertically. When it has covered a distance of $h$, the angular speed of the wheel will be: (1) $\frac { 1 } { \mathrm { r } } \sqrt { \frac { 4 \mathrm { gh } } { 3 } }$ (2) $r \sqrt { \frac { 3 } { 2 g h } }$ (3) $\frac { 1 } { \mathrm { r } } \sqrt { \frac { 2 \mathrm { gh } } { 3 } }$ (4) $r \sqrt { \frac { 3 } { 4 g h } }$
As shown in the figure, a bob of mass $m$ is tied to a massless string whose other end portion is wound on a fly wheel (disc) of radius $r$ and mass $m$. When released from rest the bob starts falling vertically. When it has covered a distance of $h$, the angular speed of the wheel will be:\\
(1) $\frac { 1 } { \mathrm { r } } \sqrt { \frac { 4 \mathrm { gh } } { 3 } }$\\
(2) $r \sqrt { \frac { 3 } { 2 g h } }$\\
(3) $\frac { 1 } { \mathrm { r } } \sqrt { \frac { 2 \mathrm { gh } } { 3 } }$\\
(4) $r \sqrt { \frac { 3 } { 4 g h } }$