Question

Question 8
One liter of water at ${30}^{\circ }C$ is mixed with one liter of water at ${50}^{\circ }C$. The temperature of the mixture will be

(a)${80}^{\circ }C$
(b) more than ${50}^{\circ }C$ but less than ${80}^{\circ }C$
(c) ${20}^{\circ }C$
(d) between ${30}^{\circ }C$ and ${50}^{\circ }C$

Answer 1

The answer is (d) between ${30}^{\circ }C$ and ${50}^{\circ }C$.

We know that,

Heat gained by the colder body = Heat lost by the hotter body

Here, heat gained by cold water will be equal to the heat lost by hot water.
So, T(cold final) - T(cold initial) = T(hot initial) - T(hot final)

T - 30 = 50 - T

Where, T is the final temperature attained.

2T = 80

$\Rightarrow$ $T={40}^{\circ }C$