## Essential University Physics: Volume 1 (3rd Edition)

We use the following equation: $W = \Delta U_{12} = GM_Em(\frac{1}{r_1}-\frac{1}{r_2})$ Thus, we find: A) $W = \Delta U_{12} = 4.4\times 10^{18}(\frac{1}{6.37 \times 10^6}-\frac{1}{4.22 \times 10^7})= 5.8 \times 10^{11} \ J$ B) $W = \Delta U_{12} = 4.4\times 10^{18}(\frac{1}{4.22 \times 10^7}-\frac{1}{3.8\times 10^8})= 9.25 \times 10^{10} \ J$