5.
[tex]m = 40 \ kg\\t = 0,4 \ s\\P = 1,5 \ kW = 1500 \W\\g = 10\frac{N}{kg}\\szukane:\\h = ?\\\\W = mgh\\i\\W =P\cdot t\\\\mgh = P\cdot t \ \ /:mg\\\\h = \frac{P\cdot t}{m\cdot g}\\\\h = \frac{1500 \ W\cdot0,4 \ s}{40 \ kg\cdot10\frac{N}{kg}}=1,5 \ m[/tex]
6.
[tex]dane:\\m = (450+50) \ kg = 500 \ kg\\h = 40 \ m\\t = 4 s\\g = 10\frac{m}{s^{2}}s\\szukane:\\P = ?\\\\P = \frac{W}{t}\\\\W = mgh\\\\P = \frac{mgh}{t}=\frac{500 \ kg\cdot10\frac{m}{s^{2}}\cdot40 \ m}{40 \ s}\\\\P=5000 \ W = 5 \ kW[/tex]
7.
[tex]dane:\\F = 600 \ N\\t =2 \ h = 7200 \ s\\P = 600 \ W\\szukane:\\s = ?\\\\W = F\cdot s\\i\\W = P\cdot t\\\\F\cdot s = P\cdot t \ \ /:F\\\\s= \frac{P\cdot t}{F} = \frac{600 \ W\cdot7200 \ s}{600 \ N}\\\\s = 7200 \ m = 7,2 \ km[/tex]
8.
[tex]dane:\\P = 6 \ kW = 6 000 \ W\\W = 7,2 \ MJ = 7 \ 200 \ 000 \ J\\szukane:\\t = ?\\\\P = \frac{W}{t}\\\\t = \frac{P}{W}\\\\t = \frac{7200000 \ J}{600 \ W} = 12 \ 000 \ s[/tex]
9.
[tex]dane:\\t = 2 \ min = 120 \ s\\h = 12 \ m\\P = 2,5 \ kW = 2500 \ W\\szukane:\\m = ?\\\\W = P\cdot t=2500 \ W\cdot120 \s = 300 \ 000 \ J\\\\W = E_{p} = mgh\\\\W = mgh \ \ /:gh\\\\m = \frac{W}{gh}\\\\m = \frac{300000 \ J}{10\frac{m}{s^{2}}\cdot12 \ m} = 2500 \ kg[/tex]
