Physics for Materials Engineering I
Young’s Modulus Experiment
Aims : To gain an understand of the concepts of stress and strain
: To measure and determine the Young’s modulus of a metal wire
Introduction
Engineers need to be extremely cognizant of the properties of the materials that they use in
their designs. When subject to a particular stress, or force per unit area, materials will respond
with a particular strain, or deformation. If the stress is small enough, the material will return
to its original shape after the stress is removed, exhibiting its elasticity. If the stress is greater,
the material may be incapable of returning to its original shape, causing it to be permanently
deformed. At some even greater value of stress, the material will break or fracture. The
particular values of stress that cause these three situations differ for every material.
where F is the force applied and A is the cross-sectional area of the material.
where L is the original length of the material, and ΔL is the change in length that results after
the stress is applied. Notice that strain is a dimensionless quantity.
Young’s Modulus, E, is a constant that describes the ratio of stress to strain for a material
experiencing either tensile or compressive stress.