Which statement describes an advantage of models? Models can be used to communicate and test designs ideas. Models always show the exact size of a system. Models have the ability to develop into complex systems. Models are useful for developing scientific methods.

Ways that industry and agriculture use physical properties to separate substances

The energy equivalent of the rest mass of an electron is

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?