I'm getting stuck to this question. Actually, how can I make a graph between relative velocity and the time? And how can I compare the two graph of the same?

Dear student,

Relative velocity ofwith respect tois given as

Let the velocities of the particles be represented as

and

Clearly(since these are the slopes of v-t curves)

Hence relative velocity=which is a straight line with positive slope. Hence it increases continuously.

Hope it helps. Regards.