Question

two trains of 120 m and 180 are running on parallel lines in the same direction with speeds 85 km/hr and 95 km/hr what time does it take to cross

Answer 1

let the length of 1st train L1= 120m
length of 2nd train L2= 180m
speed of 1st train S1=85 km/hr
speed of 2nd train S2 = 95 km/hr
now formula is
speed= distance/ time
so,
S1 + S2 = (L1 + L2)/ time
(85 + 95) km/hr = (120+180) m/ time
180 km/hr = 200 m/ time
now convert the speed from km/hr to m/s by multipying 5/18
180*5/18 = 300/ time
50 m/s = 300 m/ time
time= 300/ 50
time = 6 seconds
so the train will cross each other in 6 seconds