Two horizontal curves on a bobsled run are banked at the same angle, but one has twice the radius of the other. The safe speed (no friction needed to stay on the runfor the smaller radius curve is v. What is the safe speed on the larger radius curve?"

Newton's law of universal gravitation: Every particle in the universe attracts every other particle with a force that is proportional to the product of their masses and inversely proportional to the square of the distances between them. This force acts along the line joining the two particles.