Question

A Train 110m long moving at speed of 45 km/hr crosses a train 90m long coming from opposite direction in 10sec . Find the speed of second train.

Answer 1

Answer:

27 km/h

Step-by-step explanation:

Find the total distance:

Total distance = 110 + 90

Total distance = 200 m = 0.2 km

Find the total time taken:

Total time = 10sec = 1/360 h

Find their total speed:

Speed = Distance ÷ time

Speed = 0.2 ÷ 1/360 = 72 km/h

Find the speed of the second train:

Speed = 72 - 45 = 27 km/h

Answer: The speed of the other train is 27 km/h

Answer 2

Let there are two train A and B.
length of train A , L = 110m
speed of train A , V = 45km/h = 45 × 5/18 m/s
V = 12.5 m/s

length of train B, l = 90m
Let speed of train B is v

A/C to question,
Train A crosses tran B in 10 sec

so, relative speed = ( length of train A + length of train B)/time taken

= (110 m + 90m)/10 = 20m/s

here, both trains are moving in just opposite direction.
so, relative speed = speed of train A + speed of train B
20m/s = 12.5 m/s + speed of train B

so, speed of train B = 7.5 m/s