(a) The “lead” in pencils is a graphite composition with a Young’s modulus of 9? about 1×10? N / m2 . 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. (b) Is the answer reasonable? That is, does it seem to be consistent with what you have observed when using pencils?
Step-by-step solution 7 Step 1 of 5 (a) The radius of the graphite is half of the diametr The cross-sectional are of the graphite Step 3 of 5 When the pencil is compresed with 4N force, the length of the graphite chages. The initial length of the graphite The young’s modulus The force on one graphite pencil The cross-section area The change in length of the graphite pencil Hence, the compression in the pencil is . Step 5 of 5 (b) This result of deformation in the pencil is not reasonable; the deformation is very long which is not usually observed.