The temperature of equal masses of three different liquids A, B, C are 12∘C, 19∘C and 28∘C respectively. The temperature when A and B are mixed is 16∘C while when B and C are mixed, it is 23∘C. What would be the temperature when A and C are mixed?
20.26∘C
Let m = mass of each liquid, when A and B are mixed,
Heat lost by B = Heat gained by A
⇒ msB (19 - 16) = msA (16 - 12) ⇒ 3 sB = 4SA . . . .(1)
When B and C are mixed, Heat lost by C = Heat gained by B
⇒ msC (28 - 23) = msB (23 - 19) ⇒ 5sC = 4SB . . . .(2)
From (1) and (2), we get 16sA = 12sB = 15sC. . . .(3)
When A and C are mixed, Let θ = final temperature
Heat lost by C = heat gained by A
⇒ msC (28−θ) = msB (θ−12)
Using (3), we get
⇒ 15sC(28−θ) = 15sA(θ−12) ⇒ 16sA (28−θ) = 15sA(θ−12)
On solving for θ, we get θ = 16 × 28 + 12 × 1516+15 ⇒ θ = 20.26∘C