This Demonstration presents a computation of work done in an attractive central field, specifically Newton's inverse-square law of universal gravitation. The red disk locates the attracting mass. The plot shows the work done on the particle as it moves along a piecewise-linear path specified by the black locators.

The segments of the path are linear, which implies that the work curve is made up of parabolic arcs. The calculations are based on Newton's second law of dynamics, , where is the force, is the mass, and is the acceleration, and the differential equation for work, , where is work and is distance.