Find the length of the bridge which a train 130 m long travelling at 45 kmph can cross in 30 seconds, is :
Answer & explanation
Correct answer: option 3
Speed = \(\frac{ Distance}{ Time}\)
Let the length of the bridge be x
45 x \(\frac{5 }{ 18}\) = \(\frac{ \text{130 + Length of the bridge}}{ 30}\)
\(\frac{25 }{ 2}\) = \(\frac{ \text{130 + x}}{ 30}\)
2(130 + x) = 30 x 25
260 + 2x = 750
2x = 490
x = 245 m