Let the length of another train be L meters.
Their relative speed = (62 + 40) km/hr = 102 x (5/18) = (85/3) m/sec
? 250 + L/(85/3) = 18
? 3(250 + L)/85 = 18
? 250 + L = 510
? L = 260
? Length of another train = 260 meters
Let the speed of the train be V
According to the question.
(V + 10) x 12 = (V + 20) x 10
? 6V + 60 = 5V + 100
? x = 100 - 60 = 40 m/s
? Length of the train = (V + 10) x 12
= (40 + 10) x 12 = 600 m
Let length of the train be x m.
Relative length of the train = (x + 600) m
According to the question,
(x + 600)/30 = 30
? x + 600 = 900
? x = 900 - 600 = 300 m
Total distance to be traveled = 121 + 99 = 220 m
Relative speed = Sum of speeds = 72 km/h
= 72 x (5/18) = 20 m/s
? Required time = 220/20 = 11s
Relative speed = (32 + 40) = 72 km/h = (72 x 5/18) m/s = 20 m/s
? Length of train = (20 x 6) = 120 m
Let x be the length of the standing train
? Speed of the train = (500 + x)/20
? 100 x (5/18) = (500 + x)/20
? 500 + x = (100 x 5 x 20)/18
? 500 + x = 555.56
? x = 555.56 - 500 = 55.56 m
Relative speed of the train
= (70 - 10)
= 60 km/hr
= (60 x 5/18)
= 50/3) m/sec.
? Time taken by the train to pass the man
= (100 x 3/50) = 6 sec.
? Speed of the train = 54 x (5/18) m/sec = 15 m/sec
? Time taken by the train to cross the tunnel
= Time taken by it to cover (120 + 130) m
= (250/15) sec
= 162/3
Relative speed of both trains
= (50 - 30) = 20 km/hr
= 20 x (5/18) m/sec.
= (50/9) m/sec.
Let the length of the faster train be L
Then, (L x 9)/50 = 18
? L = (18 x 50)/9
= 100 meters
Distance covered by the train in crossing the platform
= (45 x 30) / 3600
= 3/8 km
= 375 metres
? Length of train = (375 - 100) = 275 meters
? Time taken to cross the pole
= 275 ÷ (375/30)
= (275 x 30) /375
= 30 sec
Speed of the train relative to man
= (240 + 24) km/h = 264 km/h
= 264 x (5/18) m/s = 220/3 m/s
Distance covered in passing the man = 440 m
? Time taken = (440/220) x 3 = 6 s
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