Question

Why is spring made up of steel not of copper ?

Answer 1

Because the Young's modulus of steel is greater than that of copper. Because a spring must have large restoring force when it is deformed. Therefore spring is made up of steel but not off copper.

Answer 2

A better spring will be one,in which a large restoring force is developed on being deformed. this in turn depends upon the elasticity of the material of the spring. As young modulus of Steel greater than of copper .Therefore Steel is preferred