Question

A train of length 500 metre equal along east direction with 15 metre per second. A bird is moving above it along west with speed 10 metre per second then find out the time taken by the bird to cross the train.​

Answer 1

Answer:

Explanation:

Given

Length of train = 500 metre

Speed of train = 15 metre per second in east direction

Speed of bird = 10 metre per second in West direction

By Concept of relative speed

According To Problem

=> Vr = Vt + Vb

=> Vr = 10 + 15

=> Vr = 25 metre per second

{Addition because they are in opposite directions}

Now we know that

Speed = distance \ time

So time = Distance \ speed

=> Time = 500 \ 25

=> Time = 20 seconds

Hence

Bird will cross train in 20 seconds

Answer 2

Solution :

GIVEN,

Length of train = 500 mts

Velocity of train ( towards east ) = 15mts

Velocity of train ( towards west ) = 10mts

Now , we should find relative velocity.

Note :-  Let us take the velocity of bird as positive if frame of reference is bird and the velocity of train as negative and vise versa.  

Relative velocity

= 10 - (-15)  

= 10 + 15  

= 25 m/s

Now as length of the train  = 500  

Time   = Distance ÷ Relative velocity  

= 500 ÷ 25  

= 20 sec  

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