hi

well the principle of superposition is the main principle that helps u to solve problems involving gravitation fields and mainly mechanics.it tells us that when a body is being acted by more than 1 force,we can calculate the result of the force differently.the other force wont interfere with the 1 st force.in this way we can take every force ,find its result and then take the vector sum of all the results. 

of course we can use it also in electrostatics.

it can be used to find vector sum of forces anywhere

 

hey...

thanks for replying.

but is there a criteria like only in presence of.....

by the way there was a question ..suppose if coloumb's law was

f=(Q+q)^2     /r^2.....dimensionally correct.super position principl e possible to apply