Hot water is added to three times its mass of water at 10oC and the resultant temperature is 20oC. What is the initial temperature of the hot water?
A
100oC
B
80oC
C
50oC
D
40oC
Verified Correct Answer: C.
Physical Principles & Numerical Solution
Heat loss = heat gained
mh x ch x \(\theta\)h = mc x cc x \(\theta\)c
mh x ch x (\(\theta\) - 20) = mc x cc x (20 - 10)
ch = cc ; mc = 3mh
(\(\theta\) - 20) = 3( 20 - 10)
\(\theta\) = 30 + 20
therefore, \(\theta\) = 50ºC
Source: Myschool Past Questions Archive (Record #28421)