Question

An electric train is moving on a straight and levelled track a speed of 5 km/h and passes an electric pole in 2 second. Find the time taken to pass a bridge of length 570 m.

Answer 1

_____________________________________________________________speed = 5 x 5 /18 
speed = 25 / 18 
speed = 1.38 m/s 

distance = speed x time 
distance = 1,38 x 2 
distance = 2.76 m 

2.76 m =  2 sec 

1m = 2 / 2.76 sec 

570 m = 570  x 2 / 2.76  sec

570 m = 413 sec 
_____________________________________________________________
_____________________________________________________________

Answer 2

Let Length of train = L
we know ,
distance = speed × time
Length of train = distance travelled by train in 2 sec
= 2sec × 5 km/h
= 2 sec × 5 × 5/18 m/sec
= 50/18 m

hence, Length of train = 50/18 m

we also know ,
time = distance /speed

total distance covered by train to cross bridge = (570 + 50/18 ) m

speed of train = 5 km/h
= 5 × 5/18 m/s
= 25/18 m/sec

now ,
time = ( 570 + 50/18)/(25/18) sec
= 412.4 sec

hence, time taken to pass the bridge of length 570 m by train is 412.4 sec