Physics - Rotation Question with Solution | TestHub

The correct option is (B). Concept: Angular momentum is given by $\mathrm{L}=\mathrm{m}\omega {\mathrm{r}}^2$, where $\mathrm{m}$ is the mass, $\omega$ the angular velocity and $\mathrm{r}$ is the radius of the circular motion (length of the string). If the new length is half of the original string, then the new angular momentum would be, ${\mathrm{L}}_{\mathrm{n}}=\mathrm{m}\omega {\left(\frac{\mathrm{r}}{2}\right)}^2$ Or ${\mathrm{L}}_{\mathrm{n}}=\left(\mathrm{M}\omega {\mathrm{r}}^2\right)=\frac{1}{4}=\frac{\mathrm{L}}{4}$