In an experiment, a varying force is applied tangentially for a period of time to a solid disk mounted on a frictionless axle. Initially, the disk is at rest. Which type of graph should be created so that the final kinetic energy of the disk is represented by the area under the graph?

Two identical stars with mass m orbit around their center of mass. each orbit is circular and has radius r, so that the two stars are always on opposite sides of the circle. (a) find the gravitational force of one star on the other. (b) find the orbital speed of each star and the period of the orbit. (c) how much energy would be required to separate the two stars to infinity?