Stress, Strain, and Elastic Modulus (Problem 45)

The “lead” in pencils is a graphite composition with a Young’s modulus of approximately $1.0\times {10}^9\text{N}\text{/}{\text{m}}^2.$ Calculate the change in length of the lead in an automatic pencil if you tap it straight into the pencil with a force of 4.0 N. The lead is 0.50 mm in diameter and 60 mm long.