Question 14 of 126
A brass wire of length 2 m and radius 1 mm at is held taut between two rigid supports. Initially it was cooled to a temperature of creating a tension in the wire. The temperature to which the wire has to be cooled in order to increase the tension in it to , is .
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Answer: (C) -71
Thermal stress in the wire is caused by contraction.
At -43°C, the temperature drop from 27°C is
It creates tension where is Young's modulus and is linear expansion coefficient.
For tension to increase to , the new temperature drop must be: .
Required temperature:
At -43°C, the temperature drop from 27°C is
It creates tension where is Young's modulus and is linear expansion coefficient.
For tension to increase to , the new temperature drop must be: .
Required temperature: