During a lab, we had to plot graph between Centripetal Force vs Radius of rubber stopper (some uniform acceleration lab) the result i got was a horizontal line. Then a question asks Based on your graph of centripetal force vs. radius of rubber stopper's motion, can you conclude that centripetal force is directly proportional to the radius of the rubber stoppers motion? Explain your answer. I'm just wondering if my answer makes sense. Based on our graph, it states that the theoretical centripetal force is not proportional to the radius of the rubber stoppers motion. Since Fc=m.a and a=4π²r/T² then Fc=m (4π²r/T²), basically we are only graphing the Fc’s relationship to r. This statement can only be held true if the mass is constant, and T is constant. In this case, though m stays constant, T does not, and that is why the graph does not display a direct proportionality between Fc and r.