Question

A train with speed 60km/h overtakes another train of length 225m in 72sec. If both train move towards each other then it takes 18 seconds to cross. Find the length of first train and speed of second train ​

Answer 1

Step-by-step explanation:

Time taken to cross in same direction = 72 second

Time taken to cross in opposite direction = 18 second

Speed of train X = 60 km/hr = 60 \frac{5}{18}$$ = 16.66 m/sec

Length of train Y = 225 m

Let the length of train X be l m and speed of train Y be x m/sec.

Total length = (225 + l) m

Relative speed when trains run opposite direction = (16.66 + x) m/sec

Length = speed

225 + l = (16.66 + x) 18

225 + l = 300 + 18x

l = 75 + 18x ---(1)

Relative speed when trains run opposite direction = (16.66 - x) m/sec

225 + l = (16.66 - x) 72

225 + l = 1200 - 72x

l = 975 - 72x ---(2)

By eq(1) and (2),

75 + 18x = 975 - 72x

90x = 900

x = 10 m/sec

Speed (in km/h) of Y = 10 \frac{18}{5} = 36 km/hr

Put the value of x in eq(1)

l = 75 + 18 10 = 255 m