Question

two trains of lengths 300m and 400m moving in opposite directions started crossing each other. at exactly the same moment a person standing inside the first train​

Answer 1

Given:

Given that, two trains of the lengths 300 m and 400 m are moving in opposite directions and started crossing each other. At exactly the same moment a person standing inside the first train started walking towards its engine at the rate of 5km/hr.

Also, speeds of the first is 50km/hr and and the speed second train is 35km/hr.

To find:

We need to find how much time after the trains started crossing each other did the second train cross the man walking the first train.

Solution:

According to the question, two trains moving in opposite directions started crossing each other.

So, distance $= 300 + 400 = 700$ m $= 0.7$ km

We will assume that, after $x$ hours, second train crosses the man walking in the first train.

So,

We know that, the relationship between distance and time is given by the formula, Distance $=$ Speed x Time.

Distance Covered by the Man $= 5x$ km

Distance covered by the first train $= 50x$ km

Distance covered by the second train $= 35x$ km

Then, the Total Distance $= 50x+ 35x + 5x = 90x$ km

Now equate both the distances.

$\Rightarrow 90x = 0.7$

$\Rightarrow x = \frac{0.7}{90}$

$\Rightarrow x = 0.00777$ hours

Converting hours into seconds,

$\Rightarrow x = 0.00777\times3600$

$\Rightarrow x = 28$ seconds

Therefore, in 28 Seconds, second train will cross the man walking in the first train.