Abook is sitting on a shelf that is 3.0 meters off the ground. kinetic energy is found using the formula 1/2 times mass times speed. potential energy is found by taking mass times g times height, with g as the constant, 9.8 m/s squared. what is needed to determine the mechanical energy used to move this book?

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?