C. Light travels at about 30 billion centimeters per second. A light - year is defined as the distance that light travels in a vacuum in 1 year. What is the length of a light year in meters? [1 Mark] D. Suppose you have on the surface of Earth, a sphere of cork and a sphere of lead. Each sphere has a mass of exactly 1Kg. a. Do the two spheres have the same size as well as the same mass? If your answer Yes, explain why. If your answer is No, identify the larger sphere. b. What is the weight of each? c. If you move both of them to a location on the surface of moon. What is the weight of each? What is the mass of each