Find the energy equivalents of (a) an electron of mass $9.11 \times 10^{-31} \mathrm{~kg}$, (b) a uranium atom with a mass of $4.00 \times 10^{-25} \mathrm{~kg},(\mathrm{c})$ a paper clip of mass $2.00 \mathrm{~g}$, and
(d) the Earth (of mass $5.99 \times 10^{24} \mathrm{~kg}$ ).