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Physics 06年pastpaper其中一題有關Heat

發問:

The initial temperature of a jar of juice is 80 ℃ and the mass of the juice is 2kg.Susan adds ice cubes into the jar in order to cool down the juice to 20 ℃.What is the minimum number of ice cubes at 0 ℃ required?Given : Mass of each ice cube =0.15 kgSpecific heat capacity of juice =4700J/kg/ ℃Specific heat... 顯示更多 The initial temperature of a jar of juice is 80 ℃ and the mass of the juice is 2kg.Susan adds ice cubes into the jar in order to cool down the juice to 20 ℃.What is the minimum number of ice cubes at 0 ℃ required? Given : Mass of each ice cube =0.15 kg Specific heat capacity of juice =4700J/kg/ ℃ Specific heat capacity o water = 4200J/kg/℃ Specific latent heat of fusion of ice = 3.34 x 10^5 ANS: A.8 B.9 C.10 D.11 麻煩哂各位啦!!! 更新: 請列出step,麻煩哂!!

最佳解答:

Energy lost by the juice = mc(Tf - Ti) = (2)(4700)(80 - 20) = 564 000 J For minimum number of ice cubes required, the ice should be turned to 20*C water finally. Energy gained by the ices cube = mlv + mc'T = m(3.34 X 105 + 4200 X 20) = 418 000m Assume there is no heat lost to the surroundings, heat gained by the ice = heat lost by the juice 418 000m = 564 000 m = 1.349 kg So, the number of ice cubes required = 1.349 / 0.15 = 8.995 = 9 The answer is B.

其他解答:34CDDE34D73CDF8A