12mEk\sqrt{\frac{1}{2} \mathrm{mE}_{\mathrm{k}}}21mEk
2mEk\sqrt{2 \mathrm{mE}_{\mathrm{k}}}2mEk
2 mEk\sqrt{2 \mathrm{~m}} \mathrm{E}_{\mathrm{k}}2 mEk
m2Ek\mathrm{m} \sqrt{2 \mathrm{E}_{\mathrm{k}}}m2Ek