Answer to Question #186860 in Physics for Sarunas

Question

39 liters of water at 20 ºC are mixed with 21 liters of water at 60 ºC. What is the temperature of the mixture?

Answer 1

According to thermal equilibrium equation:

$$Q_\text{lost}+Q_\text{acquired}=0,\\ cm_1(t_1-t)+cm_2(t_2-t)=0,\\\space\\ t=\frac{(m_1t_1+m_2t_2)}{m_1+m_2}=34°\text C.$$