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physics!!!急!!!

發問:

Specific heat capacity of water =4200J kg^-1 degree celsius^-1 0.2kg of hot water in a glass at 95度 fills 0.8 kg of cold water from a jar. A mixyure of warm water of 35度 is produced...........................................................................1.Find the temperature of the cold water in he jar... 顯示更多 Specific heat capacity of water =4200J kg^-1 degree celsius^-1 0.2kg of hot water in a glass at 95度 fills 0.8 kg of cold water from a jar. A mixyure of warm water of 35度 is produced. .......................................................................... 1.Find the temperature of the cold water in he jar before mixing. 2.If the temperature of the cold water in the jaris 15度 instead , how much cold water in the jar should be used to produce a final mixture of 35度 warm water?

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1) Let the temperature of the cold water be T°C. By E = mc△T and assume no energy loss to the surroundings during the process, ( 0. 2 )( 4200 )( 95 - 35 ) = ( 0. 8 )( 4200 )( 35 - T ) 12 = 28 - 0.8T 0.8T = 16 T = 20 So the cold water is 20°C. 2) Let the mass of cold water be mkg. By E = mc△T and assume no energy loss to the surroundings during the process, ( m )( 4200 )( 35 - 15 ) = ( 0.2 )( 4200 )( 95 - 35 ) 20m = 12 m = 0.6 So the required mass of cold water is 0.6kg.

其他解答:

1) 20度 2) 0.6kg
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