Problem Solving

Guys, the problem is pretty simple. However, help me please to solve it through the relative movement approach which is faster than traditional way. Thanks.


A boy walking along a road at 3mph is overtaken by a truck traveling at 40mph. If the truck breaks down 1 km beyond where it passed the boy, how many minutes after the breaks down does the boy reach the truck?

A)21,5 B) 20 C) 18(34/37) D) 18(26/43) E) 18,5

You cannot or rather should not use relative velocity concept there for the basic reason that the distance the truck travels is taken from the point it crosses the boy.

If it was given that the distance between the boy and the truck was 1 KM when the truck broke down, then definitely relative velocity would have helped but not in this case..

Could u please give a simple example with figures to understand how to apply the ideas of relative movement you mentioned. Thanks a lot in advance.