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At a fabrication plant, a hot metal forging has a mass of 75 kg and a specific heat
capacity of 430 J/(kg?C°). To harden it, the forging is immersed in 710 kg of oil that has
a temperature of 32 °C and a specific heat capacity of 2700 J/(kg?C°). The final
temperature of the oil and forging at thermal equilibrium is 47 °C. Assuming that heat
flows only between the forging and the oil, determine the initial temperature of the
forging.
(5)

Respuesta :

Answer:

940°C

Explanation:

Heat lost by the forging = heat gained by the oil

-mCΔT = mCΔT

-(75 kg) (430 J/kg/°C) (47°C − T) = (710 kg) (2700 J/kg/°C) (47°C − 32°C)

-32250 (47°C − T) = 1917000 (15°C)

47°C − T = -892°C

T = 939°C

Rounded to two significant figures, the initial temperature is 940°C.