A ball is projected vertically down with an initial velocity from a height of 20 𝑚 onto a horizontal floor. During the impact it loses 50% of its energy and rebounds to the same height. The initial velocity of its projection is

Question: A ball is projected vertically down with an initial velocity from a height of 20 𝑚 onto a horizontal floor. During the impact it loses 50% of its energy and rebounds to the same height. The initial velocity of its projection is

(A) $20ms^{-1}$

(B) $15ms^{-1}$

(C) $10ms^{-1}$

(D) $5ms^{-1}$