Question

A train travelling at 54km/h crosses a bridge in 80 seconds. What is the length of the train, if the length of the bridge is 800m ?​

Answer 1

Answer:

Given : speed =54km/hr=15m/s

Time=80 second

Total distance covered= length of bridge +length of train

So let the length of train be x

Formula used:- s=d/t

Solution:- 15m/s=(800m+x)/80sec

=>15×80=800+x

=>1200= 800+x

=>1200-800=x

=>X=400m

°.° the length of train =400m

Answer 2

Answer :-

Length of the train = 400 m

Solution :-

Speed of a train(s) = 54 Km/h

Length of the bridge = 800 m

Time taken to cross the bridge(t) = 80 seconds

Convert speed into m/s

To convert multiply speed by 5/18

Speed in m/s (s) = 54 * 5/18 = 3 * 5/1 = 3 * 5 = 15 m/s

So, speed (s) = 15 m/s

Let the length of the train be 'x' m

Distance covevered by train to cross the bridge (d) = length of the train + Length of the bridge = (x + 800) m

$\boxed{ \sf Speed =\dfrac{Distance}{Time} }$

Here

Distance covevered by train to cross the bridge (d) = (x + 800) m

Speed (s) = 15 m/s

Time taken to cross the bridge(t) = 80 seconds

$\sf \implies 15 = \dfrac{x + 800}{80}$

$\sf \implies 15 \times 80=x + 800$

⇒ 1200 = x + 800

⇒ 1200 - 800 = x

⇒ 400 = x

⇒ x = 400

Therefore Length of the train = 400 m