Odpowiedź:
Q=2000J
m1=400g=0,4kg
T1=80°
cw1=4200J/kg*°C
m2=150g=0,15kg
T2=-20°
cw2=390J/kg*°C
Qodd=cw1*m1*(T1-Tk)
Qpob=cw2*m2*(Tk-T2)
Qodd=Qpob
cw1*m1*(T1-Tk)=cw2*m2*(Tk-T2)
4200J/kg*°C*0,4kg(80-Tk)=390J/kg*°C*0,15kg(Tk+20)
134400-1680Tk=58,5Tk+1170
-1680Tk-58,5Tk=1170-134400
-1738,5Tk=-133230
Tk=76,63°C
Q=cw1*m1*ΔT+cw2*m2*ΔT
Q=ΔT(cw1*m1+cw2*m2)
ΔT=Q/(cw1*m1+cw2*m2)
ΔT=2000/(4200J/kg*°C*0,4kg+390J/kg*°C*0,15kg)
ΔT=1,15°C