(a) Starting with the mathematical expression for the gravitational force F between two point masses m1 and m2 separated by a distance r, obtain an equation in the form
logF=C−2logr,
where C is a constant for a given pair of masses.
(b) Hence prove that a graph of logF (vertical axis) versus logr (horizontal axis) is a straight line and determine its slope.
(c) The following experimental data were collected for a fixed pair of small spheres:
(r/m):1.0,2.0,4.0;
(F/N):10.0,2.50,0.625.
Using any two convenient pairs of data, calculate the slope of the straight line that would pass through the corresponding points on a logF versus logr graph and comment on its agreement with the theoretical value obtained in part (b).