The final temperature : t=77.74 °C
Given
500 g coffee, t = 80 °C
110 g aluminum cup, t = 30 °C
Required
The final temperature
Solution
Q in = Q out
Q absorbed = Q released
Q aluminum cup = Q coffee
110 x 0.9 x (t-30)=500 x 4.18 x (80-t)
99t-2970=167200-2090t
2189t=170170
t=77.74 °C