Physics specific capacity

yuet

2009-10-24 2:40 am

A 0.3 kg metal block is hearted in boiling water for some time. It is then taken out and put into a ploystyrene cup which contains 250mL of water at 25 degree Celsius. After a while, the water temperture is found to have risen by 7 degree Celsius.
It is found that the result in ther experiment is smaller than the actual specific capacity of the matal. A student proposes the following explanations. Do you agree
with each? Why?
(a) The metal is still hotter than the water in the polystyrene cup when the thermometer reading is taken
(b) The metal block carriers some of the boiling water with it when it is energy transferred
(c) The metal block loses heat to the surroundings when it is transferred.

回答 (1)

天同

2009-10-24 4:38 am

✔ 最佳答案

(a) Agree
If the metal is still hotter than the water, the heat given out by the metal is less than that used in the calculation. The would give an experimental result of specific heat capacity smaller than the actual value.

(b) Not agree
The boiling water would release heat to the mixture. There would be an under-estimation of heat given out to the water in the polystyrene cup. The experimental result of the specific heat capacity would then be larger than the actual value.

(c) Agree
Same reason as in (a). The heat given out by the metal is less than that used in the calculation. There is an over-estimation of heat given to the water in the polystyrene cup. The experimental result is therefore smaller than the actual value.

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