Question

A spring is made of steel and not of copper because
A. Steel is more elastic than copper
B. Steel is less elastic than copper
C. Steel is more plastic than copper
D. Steel is less plastic than copper

Answer 1

Hint: this question belongs to the chapter properties of material (elasticity). To the answer of this question you must know the following points
1. Definition of elasticity
2. Value of young’s modulus of elasticity of copper and steel

Complete step by step solution:
First let us see the definition of elasticity and young’s modulus of elasticity
Elasticity: it is defined as the property of a material due to which it regains or tends to regain its original shape and size after removal of deforming force
Young’s modulus of elasticity: it is defined as the ratio of stress to strain i.e. \[\dfrac{{stress}}{{strain}}\]
Now, if we look at value of young’s modulus of elasticity of steel and copper then,
Young’s modulus of elasticity of steel \[ = {\text{ }}200{\text{ }}GPa\]
Young’s modulus of elasticity of copper \[ = {\text{ }}110{\text{ }}GPa\]
A spring is good which can regain its shape and size easily on removal of deforming force and it depends on the elasticity of material from which it is made and from the above data we can see the elasticity of steel is more than that of copper, that is why spring is made of steel not copper and

Hence, the correct option will be A.

Note: Students should not confuse between elastic modulus and stiffness of the spring because elastic modulus is the intensive property of the material and stiffness is an extensive property and hence it depends on various physical dimension (length of the spring)