How much work would be done by an external agent to bring two planets (each with a mass of 1x10^20 kg) to a separation distance of 3.0x10^10 m (center to center)

b would be the answer

okay i have so many questions. but the big one here is: um wt..f is this mess? ?

pe = weightxheight = 2000x1000=2,000,000joules

luster is not a good characteristic to use by itself because luster is the property of minerals that indicates how much the surface of a mineral reflects light. the luster of a mineral is affected by the brilliance of the light used to observe the mineral surface.