1.
[tex]dane:\\v = 1,5\frac{m}{s}\\F = 400 \ N\\t = 2 \ h = 2\cdot3600 \ s = 7200 \ s\\szukane:\\W = ?\\\\P = \frac{W}{t} \ \ \rightarrow \ \ W = P\cdot t\\i\\P = \frac{F\cdot s}{t} = F\cdot v\\\\W = F\cdot v\cdot t\\\\W = 400 \ N\cdot1,5\frac{m}{s}\cdot7200 \ s\\\\W = 4 \ 320 \ 000 \ J = 4 \ 320 \ kJ = 4,32 \ MJ\\\\\\1 \ kJ = 1000 \ J\\1 \ MJ = 1 \ 000 \ 000 \ J[/tex]
2.
[tex]dane:\\m = 1 \ kg\\h_1 = 1 \ m\\h_2 = 2 \ m\\h = h_2 - h_1 = 2 \ m - 1 \ m = 1 \ m\\g = 10\frac{N}{kg}\\szukane:\\\Delta E_{p} = ?\\\\\Delta E_{p} = m\cdot g\cdot h\\\\\Delta E_{p} = 1 \ kg\cdot10\frac{N}{kg}\cdot 1 \ m\\\\\Delta E_{p} = 10 \ J[/tex]
