A man is 45 m behind the bus when the bus start accelerating from rest with acceleration 2.5 m/s2 . With what minimum velocity should the man start running to catch the bus ?
Let man will catch the bus after 't' sec. So, he will cover distance ut.
Similarly distance travelled by the bus will be 12at2. For the given condition.
ut=45+12at2=45+1.25 t2 [As a=2.5 m/s2]
⇒ u=45t+1.25 t
To find the minimum value of u
dudt = 0 so we get t = 6 sec then,
u=456+1.25×6=7.5+7.5=15 m/s.