A tray of mass M , carrying a cubical block of ice of mass m and edge L , is at rest in the middle of a gravity-free hall as shown in the figure. By what distance does the centre of mass of the "tray plus ice" system descend if the ice melts?

Step-by-step solution

In a gravity-free hall, there is no external force acting on the "tray plus ice" system. According to the principle of conservation of linear momentum, if the net external force on a system is zero, the velocity of its center of mass remains constant. Since the system is initially at rest, the initial velocity of the center of mass is zero. Therefore, the center of mass will remain at rest regardless of any internal processes, such as the melting of the ice. Hence, the displacement of the center of mass of the syst