Find minimum height of the obstacle so that the shpere can stay in equilibrium

Find the minimum height of the obstacle so, that the sphere can stay in equilibrium.

On an inclined plane, two conducting rails are fixed along the line of greatest slope. A conducting rod AB is placed on the radils so that it is horizontal. A vertically upward uniform magnetic field is present in the region. A current i flows through AB from B to A. The mass of AB is m and the coefficient of friction between the rod and rails is mu . Find the minimum and maximum value of B, so that the rod can stay in equilibrium. Assume that mu lt tan theta

On an inclined plane, two conducting rails are fixed along the line of greatest slope. A conducting rod AB is placed on the radils so that it is horizontal. A vertically upward uniform magnetic field is present in the region. A current i flows through AB from B to A. The mass of AB is m and the coefficient of friction between the rod and rails is mu . Find the minimum and maximum value of B, so that the rod can stay in equilibrium. Assume that mu lt tan theta

The minimum number of non coplanar forces that can keep a particle in equilibrium is

The minimum number of non coplanar forces that can keep a particle in equilibrium is

A closed right circular cylinder has volume 539/2 cubic units. Find the radius and the height of the cylinder so that the total surface area is minimum.