Grace is given a piece of wood, an iron nail, and a styrofoam cup. she puts these objects into a bucket of water and observes that the nail sinks to the bottom, the wood floats just under the surface, and the cup floats on top of the water. what property is being demonstrated by this experiment. a) density eliminate b) melting point c) solubility d) temperature

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?