Odpowiedzi

2010-03-21T23:37:39+01:00
Dane:
m₁ = 10kg
t₁ = 30°C
cw₁ = 4200 J :kg * °C
m₂ = 1kg
t₂ = 300°C
cw₂ = 460 J : kg * °C

Szukane
t₃ = ?

Rozwiazanie

m₁ * cw₁ * (t₃ - t₁) = m₂ * cw₂ * (t₂ - t₃)
m₁*cw₁*t₃ - m₁*cw₁*t₁ = m₂*cw₂*t₂ - m₂*cw₂*t₃
m₁*cw₁*t₃ + m₂*cw₂*t₃ = m₂*cw₂*t₂ + m₁*cw₁*t₁
t₃ * (m₁*cw₁ + m₂*cw₂) = m₂*cw₂*t₂ + m₁*cw₁*t₁
t₃ = (m₂*cw₂*t₂ + m₁*cw₁*t₁ ) : (m₁*cw₁ + m₂*cw₂)
[t₃] = [°C]
t₃ = (1*460*300 + 10*4200*30) : (10*4200 + 1*460)
t₃ = (138000 + 1260000) : (42000 + 460)
t₃ = 1398000 : 42460
t₃ ≈ 32,9 °C

t₃ - t₁ = 32,9 - 30 = 2,9°C

odp. woda ogrzeje sie o ok. 2,9°C
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