Question

21. A train 270 m long is running at a
speed of 45 km/hr. What time will it
take to cross a 130 m long bridge?​

Answer 1

Given:-

• Distance,d1 = 270 m

• Speed = 45 km/h

• Distance,d2 = 130 m

To be calculated:-

Calculate the time taken to cross a 130 m long bridge by a train .

Formula used:-

Speed = Distance/Time

Solution:-

We should convert the given velocity in metres per seconds. [ Because the distance is given in metres ]

1 km = 1000 m

45 km = 45 × 1000 m

= 45000 m

And,

1 hour = 60 minutes

= 60 × 60 seconds

= 3600 seconds

So,

45 km per hour = 45000 m / 3600 m = 12.5 m/s

Now,

Total distance = d1 + d2

= 270 + 130

= 400 m

We know that ,

Speed = Distance/Time

⇒ 12.5 = 400 / Time

⇒ Time = 400/12.5

⇒ Time = 4000/125

⇒ Time = 32 seconds

Thus,the time taken by a train is 32 seconds.

Answer 2

${\bold{\orange{\underline{ANSWER:-}}}}$

$\huge\sf\green{Given}$

• Length of the train (S$\sf{_1}$) = 270m
• Length of the bridge (S$\sf{_2}$) = 130m

☞ So, Total Length:-

• S = (S$\sf{_1}$) + (S$\sf{_2}$)
• => S = 270m + 130m = 400m

☞ SPEED = 45 km/hr = 12.5 m/s

$\huge\sf\purple{Formula}$

$time(t) = \frac{distance}{speed} \\ = > t = \frac{400}{12.5} \\ = > t = 32s$

$\bigstar\:\underline{\boxed{\bf{\red{Required\: Answer\:=32\:second}}}}$