2 liters of water at 80.c is found into a plastic bucket containing 10 liters of water at 20.c what is the final temperature of water ( density of water 1kg/litre) (neglect the heat gained by bucket and specific heat capacity of water = 1cal/gm.c ?

Answer 1

The sum of the heats gained is zero.

2*(cw)(Tf-80)+10*cw(Tf-20)=0

Now, with the magic of algebra, solve for Tf. Notice that cw, the specific heat of water divides out, and it does not enter the calculation

Answer 2

30