[tex]dane:\\m = 1 \ kg \ \ (1 \ l \ wody = 1 \ kg)\\P = 2 \ kW = 2 \ 000 \ W = 2 \ 000 \ \frac{J}{s}\\t = 3 \ min = 3\cdot60 \ s = 180 \ s\\c = 4200\frac{J}{kg\cdot^{o}C} \ - \ cieplo \ wlasciwe \ wody\\szukane:\\\Delta T = ?\\\\\\P = \frac{W}{t} \ \ \rightarrow \ \ W = P\cdot t\\oraz\\W = Q = c\cdot m\cdot \Delta T\\\\c\cdot m\cdot \Delta T = P\cdot t \ \ /:(c\cdot m)\\\\\Delta T = \frac{P\cdot t}{c\cdot m}[/tex]
[tex]\Delta T = \frac{2000 \ W\cdot180 \ s}{4200\frac{J}{kg\cdot^{o}C}\cdot1 \ kg}=\frac{2000\frac{J}{s}\cdot180 \ s}{4200\frac{J}{kg\cdot^{o}C}\cdot1 \ kg}\\\\\boxed{\Delta T \approx 85,7^{o}C}[/tex]
Odp. Woda ogrzeje się o ok. 85,7 °C.
