Question

Two goods trains of lengths 120m and 80m are running on parallel tracks towards each other at the speeds of 20km/hr and 16km/hr respectively. In how much time will they cross each other completely?

Answer 1

let the length of 1st train L1= 120m

length of 2nd train L2= 80m

speed of 1st train S1=20 km/hr

speed of 2nd train S2 = 16 km/hr

now formula is

speed= distance/ time

so,

S1 + S2 = (L1 + L2)/ time

(20+16) km/hr = (120+80) m/ time

36km/hr = 200 m/ time

now convert the speed from km/hr to m/s by multipying 5/18

36×5/18 = 200/ time

10m/s = 200 m/ time

time= 200/ 10

time = 20 seconds

so the train will cross each other in 20 seconds

plz follow me

Answer 2

Hence, the two trains completely cross each other in 10 seconds.