A hair breaks under a tension of 1.2 N. What is the diameter of the hair? The tensile strength is 2.2x10^8 Pa.

Question

A hair breaks under a tension of 1.2 N. What is the diameter of the hair? The tensile strength is 2.2 x 10^8 Pa.
m

Answer 1

Assuming no change in radius as the hair is stretched, the tensile strength (stress) T = F/A (area) so A = F/T.
A = 1.2/2.2E8 = 5.455E-9 m^2
d = 2sqrt(A/pi) = 8.334E-5 m