A passenger is standing `d` metres away from a bus. The bus begins to move eith constat acceleration `a. To catch the bus the passenger runs at a constant speed (v) towards the bus, at what minimum speed he must have ,so that he may catch the bus.

Explanation

`S_("passenger")=d+S_(bus),vt=d+(1)/(2)at^(2)`
`at^(2)-2vt+2d=0impliest=(v+-sqrt(v^(2)-2ad))/(a)`
For minimum velocity `v^(2)-2ad=0 implies v=sqrt(2ad)`