Knowledge of the modulus of elasticity of materials helps us to choose the correct material. in right dimensions for the right application. The following examples will throw light on this.
(i) Most of us would have seen a crane used for lifting and moving heavy loads. The crane has a thick metallic rope. The maximum load that can be lifted by the rope must be specified. This maximum load under any circumstances should not exceed the elastic limit of the material of the rope. By knowing this elastic limit and the extension per unit length of the material, the area of cross section of the wire can be evaluated. From this the radius of the wire can be calculated.
(ii) While designing a bridge, one has to keep in mind the following factors (1) traffic load (2) weight of bridge (3) force of winds. The bridge is so designed that it should neither bend too much nor break.