Young’s modulus

Youngs modulus

This is the ratio of tensile stress to tensile strain.
It is the gradient of the straight line in the elastic region. Its S.I unit is Nm-2 or Pa.

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Note: This holds only when the elastic limit of a material is not exceeded.

Example 3:
A wire of cross section area 3m2 increases in length from 20cm to 25cm, when a force of 5N is applied. Calculate the;
(i) tensile strain.
(ii) tensile stress
(iii) Young’s modulus

Solution:
(i) Given;lo=20cm,ln=25cm, F=5N,A=3𝑚2 𝑒=𝑙𝑛−𝑙𝑜⟺e=(25−20)=5cm
e=5/100 = 0.05m

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Example 4:
Calculate the tensile stress when a force of 25N acts on a wire of cross sectional area 5m2.

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Question:
A metallic solid of mass 45kg rests on a copper rod of cross sectional area 0.5 cm2 standing vertically as shown below,

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