from the top of multi-storeyed building ,39.2 m tall , a boy projects a stone vertically upward with an initial velocity of `9.8 ms^(-1)` such that it finally drops to the gorund (i) when will the stone reach the ground? (ii) whn will it pass through the point of projection ? (iii) what will be its velocity before striking the ground ? take g =`10ms^(-1)`
