Question

a train 360m long is running at a speed of 45km/h how much time will it take to cross a platform 140m long ​

Answer 1

✪ᴀɴsᴡᴇʀ✪

• Train will take 40 sec to cross the platform.

★ᴄᴀʟᴄᴜʟᴀᴛɪᴏɴ★

To completely cross the platform,

• First, the front of the train has to cross the platform.
• Second, the train has to travel a distance equal to its length for the whole length of the train to move out of the platform.

Thus,

$Total\:distance = (140 + 360)\:m$

$\implies Total\:distance = 500\:m$

And

$\:\:\:\:\: Speed = 45\:Km/hr$

$\to Speed = 45\times \frac{1000}{3600} \:m/s$

$\to Speed = 45\times \frac{5}{18} \:m/s$

$\to Speed = 5\times \frac{5}{2} \:m/s$

$\to Speed = 12.5\:m/s$

We have,

$\to Distance = Speed \times Time$

$\to 500\:m = 12.5\:m/s \times Time$

$\to Time = \frac{500} {12.5}\:s$

$\to Time = \frac{5000} {125}\:s$

$\to Time = 40\:s$

Answer 2

To pass a vendor standing on the platform the train must travel 400m.

45km=45000m/3600 sec=12.5m/sec

the train travels 12.5 m in 1 sec

∴, the train travels 400m in =1/12.5×400= 32 sec.