Question:Particle a is projected vertically down from the top of a tower of height 80 m with vel. ...Answer: The easiest method to solve this problem is to understand. Relative velocity of both particles will never change.This is because both of them are accelerations by the same acceleration of the earth g. Hence relative acceleration is zero.So, relative velocity during motion vAB

Time to meet In that time take the path travelled by any particle.

= 50 m from top.

Or, = 30 m from bottom.