1.
[tex]dane:\\m = 3 \ t = 3 \ 000 \ kg\\h = 1,8 \ m\\t = 6 \ h = 6\cdot3600 \ s = 21600 \ s\\g = 10\frac{N}{kg}\\szukane:\\P = ?\\\\P = \frac{W}{t}\\\\W = E_{p} =mgh\\\\P = \frac{mgh}{t}\\\\P = \frac{3000 \ kg\cdot10\frac{N}{kg}\cdot1,8 \ m}{21600 \ s}=2,5 \ W[/tex]
2.
[tex]dane:\\P = 2 \ 000 \ kW = 2 \ 000 \ 000 \ W\\v = 36\frac{km}{h} = 36\cdot\frac{1000 \ m}{3600 \ s} = 10\frac{m}{s}\\szukane:\\F = ?\\\\P = \frac{W}{t} = \frac{F\cdot s}{t} = F\cdot v\\\\P = F\cdot v \ \ /:v\\\\F = \frac{P}{v}\\\\F = \frac{2000000 \ W}{10\frac{m}{s}} = \frac{2000000 \ kg\cdot\frac{m^{2}}{s^{3}}}{10\frac{m}{s}}\\\\F = 200 \ 000 \ N = 200 \ kN[/tex]
3.
[tex]dane:\\m = 800 \ g = 0,8 \ kg\\h = 90 \ cm = 0,9 \ m\\g = 10\frac{N}{kg}\\szukane:\\E_{p}=?\\\\E_{p} = mgh\\\\E_{p} = 0,8 \ kg\cdot10\frac{N}{kg}\cdot0,9 \ m\\\\E_{p} = 7,2 \ J[/tex]
