Question

According to one set of measurements, the tensile strength of hair is 196 MPa, which produces a maximum strain of 0.400 in the hair. The thickness of hair varies considerably, but let's use a diameter of 50.0 u(mu)m . What is the magnitude of the force giving this tensile stress? If the length of a strand of the hair is 12.0 cm at its breaking point, what was its unstressed length?