A ball of mass 1kg is thrown vertically upwards from a building with a speed of 10m/s, and another ball of mass 3kg is dropped from the same point towards the ground with the same speed. At what time will the centre of mass have the maximum height w.r.t the ground? Assume balls are left at t=0.

MCQs on centre of mass and its motion, two vectors vector product, inertia moment, perpendicular and parallel axes theorems, kinematics and dynamics of rotational motion about fixed axis, rolling motion, rigid body equilibrium, torque and angular momentum.