A rectangular plank of mass `m_(1)` and height 'a' is on a horizontal surface. On the top of it another rectangular plank of mass `m_(2)` and height 'b' is placed. Find the potential energy of the system ?
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A sphere of mass m and radius r is placed on a rough plank of mass M . The system is placed on a smooth horizontal surface. A constant force F is applied on the plank such that the sphere rolls purely on the plank. Find the acceleration of the sphere.

A sphere of mass m and radius r is placed on a rough plank of mass M . The system is placed on a smooth horizontal surface. A constant force F is applied on the plank such that the sphere rolls purely on the plank. Find the acceleration of the sphere.

A plank of mass M is placed on a rough horizontal surface and a contant horizontal force F is applied on it . A man of mass m runs on the plank find the range of acceleration of the man that the plank does not move on the surface is mu .Assume that the does not slip on the plank