Itsminimum diameter is??

Question

A brass rod is to support of a load of 400N. Its elastic limit is 4 × 10^8 N/ m2 its minimum diameter must be

Ans 1.13mm

Answer 1

Elastic limit is maximum stress or force per unit area within a solid material that can arise before the onset of permanent deformation.

Stress = F/A = 4 × 108 N/ m2
F = 400N
A = πr2 = πD2/4
So,
4 × 108 N/ m2 = 400N/(πD2/4)
D2 = 400 x 4 / 3.14 x 4 × 108
D2 = 1.27 x 10-6
D = 1.13 x 10-3u200bu200bu200bu200bu200bu200bu200b m = 1.13 mm