Prob. 2.12-9. (a) Using Figs. P2.12-9 and the definition of

extensional strain given in Eq. 2.35, show that the change

in length, AL, of a thin wire whose original length is L is

given by AL= f(x) dx, where e,(x) is the extensional

strain of the wire at x. (b) Determine the elongation of a

2-m-long wire if it has a coefficient of thermal expansion

a 20 x 10 °C, and if the change in temperature along

the wire is given by AT = 10x² (°C).

+

(a) Before deformation.

(b) After deformation.

P2.12-9

AL