15g iron (c=450 J/kg K) bolt is heated from 21 C to 312 C. It is then plunged into a 2kg of 15 C water (c= 4180 J/kg K) into a 4.6kg alum. tub (c=903 J/kg K) What is the final temp. (Tf) of the water and the tub?

Question

for some reason..., i got 0.472 C for final temp of tub and -14.765 C for temp of water.....

i don't understand this question, plz help.

Answer 1

At final equilibrium, the temperatures of water, iron and tub must be equal. Assume the heat energy lost by the iron equals the heat gained by the tub and water.

You must have made some serious errors in setting up the problem. You have the water freezing by adding the heated iron.

The starting temperature of 21 C before the iron is heated makes no differense in the answer. It is what happens after it reaches 312 C and is cooled that matters.