JAMB - Physics (1987 - No. 15)
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?
100oC
80oC
50oC
40oC
คำอธิบาย
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