WAEC - Physics (2024 - No. 42)
A non-conducting vessel contains a liquid of mass 70 g at 25º C. Another 70.0g of the same liquid at 35ºC is quickly poured into the vessel. Determine the final temperature of the mixture
15ºC
20ºC
30ºC
40ºC
Explanation
Heat gained by 25º C body = Heat lost by 35º C body
M\(_c\) c \(\delta\)\(\theta\) = M\(_h\) c\(\delta\)\(\theta\)
70 x c x (f - 25) = 70 x c x (35 - f)
where f = final temperature
f - 25 = 35 - f (f and 70 cancel out)
2f = 35 + 25 = 60
f = \(\frac{60}{2}\) = 30ºC
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