Measurements of the orbital speeds of stars in the Milky Way and other galaxies have revealed that there must be a great deal of nonluminous mass in their outer reaches to make the rotational speeds remain high far away from the galactic centers. At distances of 15000 pc from the center of the Milky Way, the rotational speeds of stars is still 250 km/sec. What is the distance to the center

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jupiter is the largest planet in our solar system, having a mass and radius that are respectively, 318 and 11.2 times that of earth. suppose that an object falls from rest near the surface of each planet and that the acceleration due to gravity remains constant during the fall. each object falls the same distance before striking the ground. determine the ratio of the time of fall on jupiter to that on earth.