Tóm tắt :
\(m_1=500g=0,5kg\)
\(t_1=180^oC\)
\(m_2=400g=0,4kg\)
\(t_2=150^oC\)
\(m_3=600g=0,6kg\)
\(t_3=100^oC\)
\(V_4=10lít=0,01m^3\)
\(t_4=15^oC\)
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\(t=?\)
BL :
\(m_4=D.V_4=1000.0,01=10kg\)
Ta có : \(Q_1+Q_2+Q_3=Q_4\)
\(\Rightarrow m_1c_1\left(t-t_1\right)+m_2c_c\left(t-t_2\right)+m_3c_3\left(t-t_3\right)=m_4c_4\left(t_4-t\right)\)
\(\Rightarrow0,5.460\left(t-180\right)+0,4.380\left(t-150\right)+0,6.130\left(t-100\right)=10.4200\left(15-t\right)\)
\(\Rightarrow230\left(t-180\right)+152\left(t-150\right)+78\left(t-100\right)=42000\left(15-t\right)\)
\(\Rightarrow230t-41400+152t-22800+78t-7800=630000-42000t\)
\(\Rightarrow460t-72000=630000-42000t\)
\(\Rightarrow460t+42000t=72000+630000\)
\(\Rightarrow42460t=702000\)
\(\Rightarrow t=\dfrac{702000}{42460}\approx16,53^oC\)
Vậy nhiệt độ cân bằng là 16,53oC.
