This applet shows satellites orbiting a central body from various starting distances. the mass of the central body is much greater than the masses of the satellites. you should think of this applet as data obtained in an experiment (e. g., a set of videos made by compiling data of observations of satellites).

find the length of the major axis of the orbit of the purple satellite "ap" with initial speed 2.0 and the length of the major axis of the orbit of the red satellite "ar" with initial speed 1.5. recall that the semi-major axis of an ellipse is usually denoted ; hence we use the notation for the major axis of the purple satellite's orbit.

in the question, it gives as an app which shows these orbits. we first calculated the periods for both.

red: period = 10.7 starting radius = 2

purple: period = 3.16 starting radius = 1

which of the following techniques could be used to determine the mass "mc " of the central object, using only information available in the applet?