Question

3 kg of gold at a temperature of ${20}^{o}C$ is placed into contact with 1 kg of copper at a temperature of ${80}^{o}C$. The specific heat of gold is 1$30J/kg{\cdot }^{o}C$ and the specific heat of copper is $390J/kg{\cdot }^{o}C$. At what temperature do the two substances reach thermal equilibrium?

Answer 1

During the whole transition, the total heat energy of the system is conserved.

Hence the heat lost by copper=Heat gained by gold

$⟹m_{copper}\times s_{copper}\times \Delta T_{copper}=m_{gold}\times s_{gold}\times \Delta T_{gold}$

$⟹1\times 390\times (80-T)=3\times 130\times (T-20)$

$⟹T={50}^{\circ }C$