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JEE Main 20208 JanuaryEvening Shift
Exam
JEE Main
Year
2020
Date
8 January
Shift
Evening Shift
Subject
Physics
Chapter
Thermal Properties of Matter

JEE Main 2020 · 8 January · Evening Shift · Physics · Thermal Properties of Matter

Three containers C _ 1 , C _ 2 and C _ 3 have water at different...

Three containers C1,C2{C}_{1}, {C}_{2} and C3{C}_{3} have water at different temperatures. The table below shows the final temperature TT when different amounts of water (given in liters) are taken from each container and mixed (assume no loss of heat during the process)




































C1{C}_{1} C2{C}_{2} C3{C}_{3} TT
1l1l 2l2l −−- - 60oC{60}^{o}C
−−- - 1l1l 2l2l 30oC{30}^{o}C
2l2l −−- - 1l1l 60oC{60}^{o}C
1l1l 1l1l 1l1l θ\theta


The value of θ\theta (in oC{}^{o}C to the nearest integer) is___________

Correct answer

0

Step-by-step solution

Let θ1{\theta}_{1}, θ2{\theta}_{2} and θ3{\theta}_{3} be the temperatures of water in three containers.

1θ1+2θ2+0θ3=(1+2)601{\theta}_{1} + 2{\theta}_{2} + 0{\theta}_{3} = \left(1 + 2\right)60
θ1+2θ2=180{\theta}_{1} + 2{\theta}_{2} = 180 …. (1)
0×θ1+1×θ2+2×θ3=(1+2)300 \times {\theta}_{1} + 1 \times {\theta}_{2} + 2 \times {\theta}_{3} = \left(1 + 2\right)30
θ2+2θ3=90{\theta}_{2} + 2{\theta}_{3} = 90 …… (2)
2×θ1+0×θ2+1×θ3=(2+1)602 \times {\theta}_{1} + 0 \times {\theta}_{2} + 1 \times {\theta}_{3} = \left(2 + 1\right)60
2θ1+θ3=1802{\theta}_{1} + {\theta}_{3} = 180 …. (3)
and θ1+θ2+θ3=(1+1+1)θ{\theta}_{1} + {\theta}_{2} + {\theta}_{3} = \left(1 + 1 + 1\right)\theta
from (1)+(2)+(3)
3θ1+3θ2+3θ3=450⟹θ1+θ2+θ3=1503{\theta}_{1} + 3{\theta}_{2} + 3{\theta}_{3} = 450 ⟹ {\theta}_{1} + {\theta}_{2} + {\theta}_{3} = 150
from (4) equation 150=3θ⟹θ=50°C150 = 3\theta ⟹ \theta = 50 ° C

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