A thin horizontal circular disc is roating about a vertical axis passing through its centre. An insect is at rest at a point near the rim of the disc. The insect now moves along a diameter of the disc to reach its other end. During the journey of the insect, the angular speed of the disc.

Options

A. continuously decreases
B. continuously increases
C. first increases and then decreases
D. remains unchanged

Answer

C

Explanation

There is no external force acting on the system so angular momentum is conserved about vertical axis passing through centre. When insect is moving along the diameter from circumference to centre, moment of inertia first decreases then increases. So angular velocity will first increase then decrease.
`[:.L=Iomega=` constant]