Question

A train 55m long crosses a bridge of 220m length in 10 s. how many seconds will it take to pass a man standing on the bridge

Answer 1

Given,
Length of train($l_{t}$) = 55 m
Length of bridge($l_{b}$) = 220 m
Time required to pass the bridge($t_{b}$) = 10s
As we know, time = total distance /speed
=>($t_{b}$) = ($l_{t}$ + $l_{b}$)/speed of train
=>10 = $\frac{55+220}{speed of train}$
=> speed of train = $\frac{275}{10}$ = 27.5 m/s

now, time required to pass a man standing on bridge = total distance/speed of train
Here, we assume distance of man is 0m.
Hence, time required = $\frac{55m}{27.5m/s}$
                                  = 2s

Ans: 2 seconds

Answer 2

Given:
Length of train=55m
Length of bridge =220m
Time=10sec
Speed of train = Total Distance/ Time
=( length of bridge+ length of train)/Time
=(220+55)/10
=275/10
Speed of Train =27.5 m/ s
Considering the distance between man and train almost negligible.
Time taken to cross man=Distance/speed
=length of train/ speed of train
=55/27.5
=550m/275m/s
=2sec
Therefore , the time taken by the train to cross man standing near bridge is 2 sec.