[tex]E_{k} = \frac{mv^{2}}{2} \ \ |\cdot2\\\\mv^{2}=2E_{k} \ \ /:v^{2}\\\\\boxed{m = \frac{2E_{k}}{v^{2}}}[/tex]
[tex]E_{k} = \frac{mv^{2}}{2} \ \ |\cdot2\\\\mv^{2} = 2E_{k} \ \ /:m\\\\v^{2} = \frac{2E_{k}}{m} \ \ |\sqrt{}\\\\\boxed{v = \sqrt{\frac{2E_{k}}{m}}}[/tex]
