Answer:
(a). The magnitude of the force is 0.38416 N.
(b). The original length is 0.0869 m.
Explanation:
Given that,
Tensile strength = 196 MPa
Maximum strain = 0.380
Diameter = 50.0 μm
Length = 12.0 cm
We need to calculate the area
Using formula of area

Put the value into the formula


We need to calculate the magnitude of the force
Using formula of force

Put the value into the formula


(b). If the length of a strand of the hair is 12.0 cm at its breaking point
We need to calculate the unstressed length
Using formula of strain


Put the value into the formula

Length after expansion is 12 cm
We need to calculate the original length
Using formula of length

Put the value into the formula





Hence, (a). The magnitude of the force is 0.38416 N.
(b). The original length is 0.0869 m.