Question
A wire 3 m in length and 1 mm in diameter at 303K is kept at a low temperature of 103K and is stretched by hanging a weight of 10 kg at one end. The change in length of the wire is (Y = 2× 1011 Nm−2, g = 10 m s−2 and = 1.2× 10−5 K−1)
Answer: Option A
:
A
The contraction in the length of the wire due to change in the temperature
=αLΔT
=1.2×10−5×3×(103−303)
=−7.2×10−3m
The expansion in the length of wire due to stretching force
=FLAY=(10X10)X3(0.75×10−6)(2×1011)
=2×10−3m
Resultant change in length
=−7.2×10−3+2×10−3
=−5.2×10−3
=-5.2 mm
Negative sign shows contraction
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:
A
The contraction in the length of the wire due to change in the temperature
=αLΔT
=1.2×10−5×3×(103−303)
=−7.2×10−3m
The expansion in the length of wire due to stretching force
=FLAY=(10X10)X3(0.75×10−6)(2×1011)
=2×10−3m
Resultant change in length
=−7.2×10−3+2×10−3
=−5.2×10−3
=-5.2 mm
Negative sign shows contraction
Was this answer helpful ?
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