For each of the following pairs of polymers, do the following: (1) State whether it is possible to determine whether one polymer
1 answer:
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Answer:
a) The mean stress experimented by the aluminium part is 100 megapascals, b) The stress amplitude of the aluminium part is 400 megapascals, c) The stress ratio of the aluminium part is 4.
Explanation:
a) The mean stress is determined by this expression:
Where:
- Mean stress, measured in megapascals.
- Minimum stress, measured in megapascals.
- Maximum stress, measured in megapascals.
If we know that and
, the mean stress is:
The mean stress experimented by the aluminium part is 100 megapascals.
b) The stress amplitude is given by the following difference:
Where is the stress amplitude, measured in megapascals.
If we know that and
, the stress amplitude is:
The stress amplitude of the aluminium part is 400 megapascals.
c) The stress ratio () is the ratio of the stress amplitude to mean stress. That is:
If we know that and
, the stress ratio is:
The stress ratio of the aluminium part is 4.
Answer:
A=False
B=False
C=False
D=False
E=False
F=False
Explanation:
A. In an isothermal process, only the reversibly heat transfer is 0,
B. Consider the phase change of boiling water. Here, the temperature remains constant but the internal energy of the system increases.
C. This is not true even in reversible process, as can be inferred from the equation in part A.
D. This is only true in reversible processes, but not in all isothermal processes.
E. Consider the phase change of freezing water. Here, the surroundings are increasing their entropy, as they are taking in heat from the system.
F. This is not true if , like in answer B. One case where this is true is in the reversible isothermal expansion (or compression) of an ideal gas.