A 0.2 kg glass cup at 20 C is filled with 0.4 kg of hot water at 70 C. Neglecting any heat losses to the environment, what is the equilibrium temperature?

Answer 1

c1 = 700 J/kg•degr,
c2 = 4180 J/kg•degr,
m1 = 0.2 kg,
m2 = 0.4 kg.
Q1 =c1•m1•(T-20),
Q2 = c2•m2•(70-T)
Q1=Q2.
700•0.2•(T-20) = 4180•0.4•(70-T)
Solve for T