3.
[tex]dane:\\m = 5 \ kg\\v = 5\frac{m}{s}\\szukane:\\W = ?\\\\W = E_{k} =\frac{1}{2}mv^{2}\\\\W = \frac{1}{2}mv^{2}\\\\W = \frac{1}{2}\cdot5 \ kg\cdot(5\frac{m}{s})^{2}\\\\W = 62,5 \ J[/tex]
