Question

Explain experimental determination of Young's modulus.​

Answer 1

Explanation:

Theory

The normal stress for a wire with length L and radius r is loaded with weight Mg where l is the increase in length, then normal stress is given as:

Normal stress = \(\frac{Mg}{\pi r^{2}}\)

Longitudinal strain = \(\frac{l}{L}\)

Hence, Young’s modulus = \(\frac{normal\;stress}{longitudinal\;strain}\) \(Y=\frac{\frac{Mg}{\pi r^{2}}}{\frac{l}{L}}\) \(Y=\frac{MgL}{\pi r^{2}l}\)

Y can be calculated as the values of L and r are known and l is found by known Mg value.