Question

ratio of stress to strain remsins constant if the external force is constant ?
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Answer 1

Explanation:

The ratio of stress to strain is always constant. If stress is increased, strain will also increase so that their ratio remains constant.

Answer 2

Let L be the length, r be the radius of the wire.

Volume of the wire is

V=πr

2

L

Differentiating both sides, we get

ΔV=π(2rΔr)L+πr

2

ΔL

As the volume of the wire remains unchanged when it gets stretched, so ΔV=0. Hence

0=2πrLΔr+πr

2

ΔL

∴

ΔL/L

Δr/r

=−

2

1

Poisson

′

sratio=

Longitudinalstrain

Lateralstrain

=−

ΔL/L

Δr/r

=

2

1

=0.5