Read the following statements regarding the rotational motion of a system: (A) If the Earth were to suddenly shrink to half its present radius without any change in mass, the duration of the day would decrease. (B) The rotational kinetic energy of an isolated collapsing star remains conserved during its contraction. (C) An ice skater pulling her arms inward decreases her moment of inertia to spin faster. (D) The angu

Step-by-step solution

Statement (A) is correct. If the Earth shrinks, its moment of inertia I decreases. By conservation of angular momentum ( L = I = constant ), its angular velocity must increase. Since the time period T = 2 , the duration of the day decreases. Statement (B) is incorrect. For an isolated collapsing star, angular momentum L is conserved, but as it contracts, its moment of inertia I decreases. The rotational kinetic energy is given by K = L^2 2I . Since I decreases, the kinetic energy increases. It is not conserved. Sta