What is the Final Temperature of a Water Mixture?

[fallen186]

Homework Statement

You pour a certain amount of water at 100C and an equal amount of water at 20C into an insulated container. THe final temperature of the mixture will be (a) 60C (b) Less than 60C (c) greater than 60C.

Homework Equations

The Attempt at a Solution

I don't know what formula to use. Can someone give me a hint.

 

[Delphi51]

The usual approach on these heat questions is to write this formula:
Heat lost by first material = Heat gained by second material

I trust you have a formula for calculating the heat when you have the temperature change.

 

[Kurdt]

Surely you have been learning about this in class. If not the correct equations are easily found with a google search.