Question
A 4m long wire of radius 4 mm is elongated by 0.01% when loaded by a force of 80π newton. What is the stress in the wire and Young's modulus of wire?
Solution
Length of the wire, l = 4m
Radius of the wire, r = 4 mm = 0.004 m
Force on the wire, F = 80
Strain = 0.01% = 0.0001
Now, using the formula of stress,
=
Young's modulus of the wire is given by,
Y =