Question
A man is at a distance of 6 m from a bus. The bus begins to move with a constant acceleration of 3ms.In order to catch the bus, the minimum speed with which the man should run towards the bus is
2 m s-1
4 m s-1
6 m s-1
8 m s-1
Solution
C.
6 m s-1
If the man did not run, the bus would be at a distance s1 at time t given by
s1 = 6 + t2
= 6 + × 3 × t2
s1 = 6 + t2
If v is the speed of man, he would cover a distance s2 = vt in time t.
To catch the bus,
s1 = s2
6 + t2 = v t
⇒ t2 t + 4 = 0
which gives
t =
Now t will be real if is positive or zero.
Minimum v corresponds to = 0 which gives v = 6 m s-1
