$A$ person is rotating on a rotating table with their arms held down. Suddenly,they spread their arms out. What happens to their angular momentum?

Two identical beads are placed at vertex $A$ of an equilateral triangle $ABC$ made of a uniform wire. The triangle is rotated about the axis $AO$. The beads are then released from rest and move along $AB$ and $AC$ respectively (see figure). Neglecting friction,which of the following quantities will be conserved during the downward motion of the beads?

$A$ horizontal platform is rotating with uniform angular velocity around the vertical axis passing through its centre. At some instant of time, a viscous fluid of mass $m$ is dropped at the centre and is allowed to spread out and finally fall off. The angular velocity during this period

$A$ thin uniform circular disc of mass $M$ and radius $R$ is rotating with angular velocity $\omega$ in a horizontal plane about an axis passing through its centre and perpendicular to its plane. Another disc of the same radius but of mass $\frac{M}{2}$ is placed gently on the first disc co-axially. The new angular velocity will be

An ice block is placed at the center of a circular table. The system is rotated about the axis of the table with an angular velocity $\omega$. If the ice starts melting without evaporation,the rotational speed of the system will:

If the radius of the Earth becomes $1/n^{th}$ of its present value,without any change in its mass,then the duration of the day becomes: