Semi-trailer trucks have an odometer on one hub of a trailer wheel. the hub is weighted so that it does not rotate, but it contains gears to count the number of wheel revolutions—it then calculates the distance traveled. if the wheel has a 1.30 m diameter and goes through 300,000 rotations, how many kilometers should the odometer read?

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?