Which one of the following statements is true? Explain.
A. When materials are subjected to a tensile stress, the lateral strain is always negative.
B. When metals are subjected to a tensile stress, the lateral strain is always positive.
C. When materials are subjected to a tensile strain, the lateral strain is always negative.
D. When metals are subjected to a tensile stress, the strain is always proportional to the magnitude of the stress.
E. When materials are subjected to a compressive stress, the Young's Modulus is always positive.

All the given option is false.

Explanation:

A)

This is not true for all the materials like composite because the Poisson ratio for composite material can be negative that is why positive tensile stress may produce positive lateral strain.

B)

This is not true for all the material because the Poisson ratio for some material can be positive  that is why positive tensile stress may produce negative lateral strain.

C)

The explanation is same as option A.

D)

This is not true for all the materials ,It is valid only up to elastic limit .After the elastic limit the strain and stress does not follow linear path.

E)

This is not true for all the materials because some materials like composite is having negative value of Young's modulus.

Therefore all the given option is false.

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