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A suspended fibre was stretched by an increasing load attached to the bottom end. Then it was allowed to contract by slowly reducing the load. A stress-strain graph was obtained as shown. Which one of the following conclusions may be deduced from the graph?
(1) All the work done in stretching the fibre is converted into potential energy.
(2) More work is done in stretching than is recovered in contracting.
(3) The temperature of the fibre rises after it has been stretched and allowed to contract for a few times.
Why the statement (3) is not true?
更新1:
The correct are (1) and (2) only.
更新2:
Sorry, the correct answer is (2) and (3) = =""
更新3:
I think you have found that the given answer (1) is wrong, and (3) seems to be correct, and you have tried to explain why it is not true......anyway, thanks for your help..you always help me so much:)
