Apply the concept of relative velocity

[winnie3]

I cannot understand how to apply the concept of relative velocity in certaijn questions like the below one
the question is Two trains A and B of length 400m each are moving on two parallel tracks with a uniform speed of 72km/hr in the same direction with A ahead of B The driver of B decides to overtake A and accelerates byt 1m/s2 If after 50s the guard of B just brushes past the driver of A, what was the original distance between them?
sir, I know that train B's acceleration is 1m/s^2 time is 50s initial velocity is O and by equations of motion we can find the distance. But my teacher said here the concept of relative velocity comes into play. Please explain me why and how?

 

[Gib Z]

This shouldn't be in the Tutorials section. This section is for knowledgeable people to post tutorials.

To your question,

We can take them to both be going at v=0 yes? Relative to each other.

O btw, a is constant, 1, we can use the equations now. s=ut + (at^2)/2. Let a=1 and make other relavent substitutions.

Moderator, move this thread please.

Edit: I just realized i sounded really cold in that post, no disrespect winnie3, hope u have fun here at physicsforums.com :)

 

[m2003]

The concept of relative velocity is used to describe the motion of one object with respect to another object. In this scenario, the relative velocity between trains A and B is the difference in their velocities. As train B accelerates, its velocity increases and the relative velocity between the two trains also increases.

To apply the concept of relative velocity in this question, we can consider the motion of train B with respect to train A. Initially, train B is moving at the same speed as train A, so their relative velocity is 0. However, as train B accelerates, its relative velocity with respect to train A increases by 1m/s every second.

After 50 seconds, the guard of train B brushes past the driver of train A. This means that the distance between the two trains has reduced to 0, and their relative velocity is equal to the sum of their individual velocities. Using the equations of motion, we can calculate the distance between the two trains at this point.

Therefore, the concept of relative velocity helps us to understand the motion of train B with respect to train A and how it changes as train B accelerates. It allows us to consider the motion of two objects in relation to each other, rather than just their individual motions.