Question

A train moving with a speed of 36 kmph takes 14 s to cross a bridge of length 100 m. The length of the train is

• A. 140 m
• B. 40 m
• C. 100 m
• D. 360 m

Answer 1

Answer: (B)

40 m

Answer 2

Here, $v = 36 \, km \, h^{-1} = 36 \times \frac{5}{18} = 10 \, m \, s^{-1}$
Length of bridge, $I = 100\, m$
Time taken by train to cross the bridge, $t= 14 s$
Let the length of the train be $x$ m.
$\therefore \:\:\:\: v = \frac{(x + l)}{t}$
or , $x = v \times t - l$ or , $x = 10 \times 14 = 100 = 40 \, m$