Imagine repeating the experiment in an airless tube, or vacuum. Would this change the result? If so, how?

How many times did thomas edison mess up the light bulb

Which planet do you think would be easiest for humans to colonize some day?

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?