The ideal pendulum is formed by a sphere E of mass m, attached to one end of an ideal string whose other O end is fixed to the Earth. The sphere is released from rest, from the horizontal position shown in the figure. When it reaches the lowest point of its trajectory it crashes with block B, of unknown mass, which is located Resting. Suppose that this collision can occur from only two forms: it can be perfectly elastic or perfectly inelastic. Determine what the value of mass B must be, so that after the collision the pendulum reaches the same height in either of the two possible cases.