Question

a train 320m long takes 40 seconds to cross a bridge . find the length of the bridge if speed of the train is 45km/hr​

Answer 1

Answer:

180m

Step-by-step explanation:

Let the length of bridge be x

(i)

Given - a train 320m long and speed of the train is 45km/hr

$45 \frac{km}{hr} = 45 \times \frac{5}{18} \frac{m}{sec} = 12.5 \frac{m}{sec}$

(ii)

Given - train takes 40 seconds to cross a bridge.

therefore ,

total length = length of train + length of bridge

= ( 320 + x ) m

total time = 40 sec

Therefore ,

Length of bridge =

$(320 + x) m \: = 40 sec\times 12.5 \frac{m}{sec}$

$320 + x = 500m$

$x = 500 - 320m$

$x = 180m$

Answer 2

Answer:

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Answer:

180m

Step-by-step explanation:

Let the length of bridge be x

(i)

Given - a train 320m long and speed of the train is 45km/hr

45 \frac{km}{hr} = 45 \times \frac{5}{18} \frac{m}{sec} = 12.5 \frac{m}{sec}45

hr

km

=45×

18

5

sec

m

=12.5

sec

m

(ii)

Given - train takes 40 seconds to cross a bridge.

therefore ,

total length = length of train + length of bridge

= ( 320 + x ) m

total time = 40 sec

Therefore ,

Length of bridge =

(320 + x) m \: = 40 sec\times 12.5 \frac{m}{sec}(320+x)m=40sec×12.5

sec

m

320 + x = 500m320+x=500m

x = 500 - 320mx=500−320m

x = 180mx=180m