Question

In two beakers ($A$ and $B$) $50ml$ water of about ${70}^{o}C$ each is taken. Then in beaker $A,50ml$ of water of about ${30}^{o}C$ is added and after $5$ minutes, in beaker $B,50ml$ of water about ${30}^{o}C$ is added. What would be observed if the temperature of both beakers are recorded immediately? Why?

Answer 1

In $A$ since the temperature of the water will get down immediately after adding water at ${30}^{o}C$, the difference in temperature between the water in $A$ to the atmosphere is less so the heat transfer rate between the beaker $A$ and atmosphere will reduce.

Whereas in the case of beaker $B$, the temperature is higher for five minutes so the heat transfer rate from $B$ will be high, and then ${30}^{o}C$ water is added which reduces the temperature further.

So after 5 minutes temperature of $B$ will be less than $A$.