An object's time to roll down an incline is influenced by its moment of inertia. A solid sphere, possessing a lower moment of inertia than a hollow sphere, accelerates faster and consequently reaches the incline's base sooner. Based on rolling motion equations, the solid sphere's descent time will be shorter than the hollow sphere's due to its greater rotational inertia.
Final Answer: \( t_1<t_2 \).
A small bob A of mass m is attached to a massless rigid rod of length 1 m pivoted at point P and kept at an angle of 60° with vertical. At 1 m below P, bob B is kept on a smooth surface. If bob B just manages to complete the circular path of radius R after being hit elastically by A, then radius R is_______ m :