2.
[tex]dane:\\m = 5 \ kg\\v = 1\frac{m}{s}\\szukane:\\E_{k} = ?\\\\\\E_{k} = \frac{1}{2}mv^{2}\\\\E_{k} = \frac{1}{2}\cdot5 \ kg \cdot(1\frac{m}{s})^{2}\\\\\underline{E_{k} = 2,5 \ J}[/tex]
3.
[tex]dane:\\W = 10 \ J\\t = 2 \ min = 2\cdot60 \ s = 120 \ s\\szukane:\\P = ?\\\\P = \frac{W}{t}\\\\P = \frac{10 \ J}{120 \ s}\\\\\underline{P \approx 0,08(3) W \approx83,3 \ mW}[/tex]
4.
[tex]dane:\\m = 8 \ kg\\h = 2 \ m\\g = 10\frac{N}{kg}\\szukane:\\E_{p} = ?\\\\\\E_{p} = mgh\\\\E_{p} = 8 \ kg\cdot10\frac{N}{kg}\cdot2 \ m\\\\\underline{E_{p} = 160 \ J}[/tex]