\(E=m c^{2} \quad\) or \(\quad m=\frac{E}{c^{2}}\)

Mass decay per second

\( = \frac{{\Delta m}}{{\Delta t}} = \frac{1}{{{c^2}}}\frac{{\Delta E}}{{\Delta t}} = \) \(\frac{P}{{{c^2}}} = \frac{{1000 \times {{10}^3}{\text{W}}}}{{{{\left( {3 \times {{10}^8}{\text{m}}/{\text{s}}} \right)}^2}}}\)

\({=\frac{10^{6}}{9 \times 10^{16}} \mathrm{kg} / \mathrm{s}}\)

Mass decay per hour

\(=\frac{\Delta m}{\Delta t} \times 60 \times 60=\left(\frac{10^{6}}{9 \times 10^{16}} \mathrm{kg} / \mathrm{s}\right)(3600 \mathrm{s})\)

\(=4 \times 10^{-8} \mathrm{kg}=40 \times 10^{-6} \mathrm{g}=40 \mu \mathrm{g}\)