To complete the first setup on a new machine took an employee 280 minutes. Using an 75% cumulative averageminustime learning curve indicates that the second setup on the new machine is expected to take ___

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?