Question

if trains are of length 100m and moving with a speed of 20m/s each when they will cross each other while moving in opposite direction

Answer 1

Answer:

Length of both the train is same, that is, 100 m.

The speed of trains are so same, that is , 20 m/s.

Both are moving in opposite direction.

We need to find : Time taken by them at which they will cross each other.

Solution :

The relative speed of the trains : 20 + 20 = 40 m/s.

So, time taken by the trains to cross each other :

⇒ Sum of the lengths of the trains/Relative speed

⇒ (100 + 100)/40

⇒ 200/40

⇒ 20/4

⇒ 5 s

Hence, the time taken by the trains to cross each other ka 5 seconds.

Answer 2

$\underline{\rm\red{Question - }}$

The trains of length 100m are moving with speed of 20 m/s each. When they will cross each other while moving in opposite directions towards each other.

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$\underline{\rm\red{Answer }}$

$\underline{\rm\pink{Given - }}$

• Length of each train = 100 m

Velocity of each train = 20 m/s

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$\underline{\rm\pink{To\: find - }}$

• Time after which they will cross each other.

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$\underline{\rm\red{Solution - }}$

The trains are moving in opposite direction. So lets take the velocity of 1st train as positive ( means the train is moving in positive direction ) amd velocity of 2nd train as negative ( means train is in opposite direction to that of positve direction )

Relative velocity = Velocity of 1st train - Vecloity of 2nd train

Relative velocity = 20 m/s - ( - 20 m/s )

( as the train is in opposite direction )

Relative veloicty = 40 m/s

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Now, the train are crossing each other this means that the total distance will be equal to the sum of length of both trains.

Total length = 100 m + 100 m

Total length = 200m

We know that,

Time = Distance/Velocity

Time taken = 200/40

Time after which they will cross each other = 5 sec.

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