Do jakiej temperatury grzałka o mocy 150 W w ciągu 30s ogrzeje 1l wody o temperaturze 30°C.

[latex]dane:\P = 150 W\t = 30 s\T_1 = 30^{o}C\m = 1 kg (1 litr wody=1 kg)\C = 4200frac{J}{kg*^{o}C}\szukane:\T_2 = ?[/latex] [latex]P = frac{W}{t}\W = P*t\\W = P*t\i\W = Q=C*m*(T_2-T_1)\\C*m*(T_2-T_1)=P*t\\C*m*T_2 - C*m*T_1 = P*t\\C*m*T_2 = C*m*T_1+P*t /:C*m[/latex] [latex]T_2 = frac{C*m*T_1+P*t}{C*m}\\T_2 = frac{4200*1*30+150*30}{4200*1} ^{o}C = frac{130500}{4200}^{o}C = 31,07^{o}C\\T_2 approx 31,1^{o}C[/latex]