A spacecraft of mass 2000kg moves from a circular orbit of radius 5RE to another of radius 2RE about Earth (RE=6.4×106m). Using G=6.67×10−11Nm2kg−2 and ME=6.0×1024kg, calculate the change in its gravitational potential energy ΔU=Ufinal−Uinitial.
(a) +3.8×1010J
(b) −3.8×1010J
(c) −1.9×1010J
(d) −7.5×1010J