body dropped from the top of a tower and after 'n' seconds another stone is thrown downwards with velocity ' v '. They can meet after a time of :

                                   { (gn/2 - v) / (gn - v) }n

 

bus accelerates at a constant rate 'a' from rest. man standing at a distance of 'd' away from the bus should run at a minimum velocity of v = (2ad) to get to the bus.