Question

Two trains 137 metres and 163 metres in length are running towards each other on parallel lines, one at the rate of 42 kmph and another at 48 kmph. In what time will they be clear of each other from the moment they meet?

Answer 1

Answer:

They will be clear of each other from the moment they meet 13.2 seconds after.

Step-by-step explanation:

To solve this problem we need to know the relative speed and the distance between the trains.

So, we have:

Relative speed = 42 + 48 = 90 km/h =

= (90 x $\frac{5}{18}$) m/s = 25 m/s

Distance = 137 + 163 = 330 m

Now we know that:

Time = $\frac{distance}{speed}$

Then:

Time = $\frac{330}{25}$ = 13.2 s

Hence, they will be clear of each other from the moment they meet 13.2 seconds after.

Answer 2

The time when both the train meet each other is 12.25sec.

Given:-

Length of first train = 137m

Length of second train = 163m

Speed of first train = 42km/h

Speed of second train = 48km/h

To Find:-

The time when both the train meet each other.

Solution:-

We can easily find out the value of time when both the train meet each other by using these simple steps.

As

Length of first train (l1) = 137m

Length of second train (l2) = 163m

Speed of first train (v1) = 42km/h

Speed of second train (v2) = 48km/h

Here, first we have to convert speed from km/h to m/s as the length is given in meters by multiplying both the speeds by 5/18

Speed of first train (v1) = 42×5/18 = 2.3×5 = 11.5m/s

Speed of second train (v2) = 48×5/18 = 2.6×5 = 13m/s

Now, Total speed (v) = v1 + v2 = 11.5+13 = 24.5m/s

Total distance (d) = l1 + l2 = 137+163 = 300m

Also, according to the formula,

$speed = \frac{distance}{time}$

$time = \frac{distance}{speed}$

$t = \frac{d}{v}$

$t = \frac{300}{24.5}$

$t = \frac{3000}{245}$

$t = 12.25$

Hence, The time when both the train meet each other is 12.25sec.

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