Two substances of masses m and 2m, specific heat 2c . . .

Question : Two substances of masses m and 2m, specific heat 2c and c respectively are at temperature T1 and T2. If these are brought in contact then find the temperature of mixture at thermal equilibrium if T1>T2.


Doubt by Muskan

Solution : 
Let T be the temperature of mixture at thermal equilibrium.

According to the principle of Calorimetry

Heat lost by the Hot body = Heat gained by the cold body

m1c1ΔT1=m2c2ΔT2
m(2c)(T1-T)=2m(c)(T-T2)
T1-T=T-T2
T1+T2=T+T
T1+T2=2T
T = (T1+T2)/2