[tex]dane:\\m = 60 \ kg\\W = 3 \ kJ = 3 \ 000 \ J\\szukane:\\v = ?\\\\Rozwiazanie\\\\W = E_{k} = \frac{mv^{2}}{2}\\\\W = \frac{mv^{2}}{2} \ \ /\cdot2\\\\mv^{2} = 2W \ \ /:m\\\\v^{2} = \frac{2W}{m}\\\\v = \sqrt{\frac{2W}{m}}\\\\v = \sqrt{\frac{2\cdot3000 \ J}{60 \ kg}} = \sqrt{\frac{6000 \ kg\cdot m^2/s^{2}}{60 \ kg}}=\sqrt{100\frac{m^{2}}{s^{2}}}}= 10\frac{m}{s}[/tex]
