200g of water at 90^\circC is mixed with 100g of water at 30^\circC. What is the final temperature?
A
50oC
B
60oC
C
70oC
D
80oC
Verified Correct Answer: C.
Physical Principles & Numerical Solution
Heat lost = heat gained
200 x c x (90 - \(\theta\))= 100\(\times\) c \(\times\) (\(\theta - 30\))
Dividing through by 100c, we have
2(\(90 - \theta\)) = (\(\theta - 30\))
simplifying, we have
\(\theta\) = 70^\circ
Source: Myschool Past Questions Archive (Record #27988)