Question

The force of attraction between two magnets is F Newtons. This force is inversely proportional to the square of the distance

Answer 1

As, F is inversely proportional to square of distance between them
a) When it will be doubled the force will reduce 4 times
ie. 10/4 =2.5
b) i) F= k*1/d²
ii)  k=3² *2= 18
 Therefore F= 18/5² =18/25 =0.72