Odpowiedź :
[tex]dane:\\P = 0,35 \ kW = 350 \ W\\W = 0,42 \ MJ = 420 \ 000 \ J\\szukane:\\t = ?\\\\P = \frac{W}{t} \ \ \rightarrow \ \ t = \frac{W}{P}\\\\t = \frac{420000 \ J}{350 \ W} = 1200 \ s = 20 \ min[/tex]
[tex]dane:\\P = 0,35 \ kW = 350 \ W\\W = 0,42 \ MJ = 420 \ 000 \ J\\szukane:\\t = ?\\\\P = \frac{W}{t} \ \ \rightarrow \ \ t = \frac{W}{P}\\\\t = \frac{420000 \ J}{350 \ W} = 1200 \ s = 20 \ min[/tex]