Question

The ratio of the speeds of a train and a man is 6:1. The length of the train is 650 m
and crosses a pole in 1 minute 5 seconds. In how much time will the man cross the
240m long platform?​

Answer 1

Answer:

2.5 mins or 2 min 30s

Step-by-step explanation:

Ratio of velocity of train and man = 6:1

Length of train(L) = 650m

Length of platform(L’) = 240m

time taken by train to cross a pole (which we are considering to be of negligible length ) = 1 min 5 sec or 65 s

In other words, the train travels its length in 65s

[As, by the formula v=(L+L’/t) here L’ = 0; so v = L/t]

speed of train = 650/65 = 10m/s

Now man’s speed is simply 1/6 of train velocity, as indicated by the ratio,

so speed of man = 10/6 = 1.6m/s

So, time taken by the man to cross 240 m platform at constant speed

then time is 240/1.6 m/s

= 150 s = 2.5 mins or 2 min 30 s

Answer 2

Answer:

2 min 24 sec

Step-by-step explanation:

Given:

i)The ratio of the speeds of a train and a man is 6:1.

ii)The length of the train is 650 m

and crosses a pole in 1 minute 5 seconds.

To find :

time taken by the man to cross the

240m long platform.

Solution:

[1] Train:

●Length of train = 650m

●Time taken = 1 min 5sec = 65sec

We know that,

Speed = Distance/ Time

But, particularly about train, the formula is written as:

Speed of train= Train length / time taken

∴Speed of train = 650/ 65

∴Speed of train = 10m/s

[2] Man:

●Length of platform = 240m

●Let the time taken by man to cross the platform be 't' sec.

∴Speed of man = Length of platform / time taken

= 240/t m/s

Now,

According to the given condition,

Speed of train/Speed of man = 6/1

$\frac{10}{ \frac{240}{t} } = \frac{6}{1}$

$10 = \frac{240}{t} \times 6$

$t = \frac{240}{10} \times 6$

$∴t = 144 \: sec$

$∴t = 2 \: min \: 24 \: sec$