将A、B混合后
A 吸收的热量 = B 放出的热量
M1*C1*(21-15) = M2*C2*(25-21)
3*M1*C1 = 2*M2*C2
M1 C1 = (2/3) M2 C2
同理 对 B C 混合
M2 C2 (32-25) = M3 C3 (35 -32)
7 M2 C2 = 3 M3 C3
M3C3 = (7/3) M2 C2
设 将A、B、C混合后的温度 为 T
每个物体的热量变化均可表示为
Q = MC(T-T0)
如果 T > T0 ,则 Q > 0,表示吸热,反之表示放热.
“整个”体系的热量变化为0
M1C1(T-15) + M2C2(T-25) + M3C3(T-35) = 0
(2/3)M2C2 (T-15) + M2C2(T-25) + (7/3)M2C2(T-35) = 0
(2/3)(T-15) + (T-25) + (7/3)(T-35) = 0
2(T-15) + 3(T-25) + 7(T-35) = 0
12T - 350 = 0
T = 29.17 度