Question

Why is steel more elastic than rubber?

Answer 1

Hint: Elasticity is the ability to a body to return to its previous state when an external stress and strain is applied on it. A body is said to be more elastic if it returns to its original configuration faster than others.

Complete step-by-step answer:
Stress is defined as an external force which causes a change in the object. It is force applied on the object per unit area.
$\sigma ={\displaystyle \frac{F}{A}}$
where the applied stress is signified by $\sigma$, the force applied is F and the cross-sectional area is A. The unit of stress is $N/m^2$ in S.I. system
Corresponding to stress, we have strain which is the amount of change or deformation happening in the object due to application of stress. We can define strain as follows:
$\epsilon ={\displaystyle \frac{\delta l}{L}}$
where $\delta l$ represents the elongation produced in the material and L represents the original length of the material. Strain does not have any unit.
Elasticity of a material can be defined as the ability of a material to regain its original shape after an external force is applied on it. The ratio of stress applied on a body to the strain produced in it is defined as the Young’s modulus of that material.
Now, when we apply equal amounts of stress on steel and rubber having the same cross-sectional area, we notice that compared to steel, rubber gets stretched. The strain produced in rubber is much larger compared to that in steel. This means that steel has a larger value of Young’s modulus of elasticity and hence, steel has more elasticity than rubber.

Note: Greater the resistance to change, greater is the elasticity of that material. Rubber gets stretched because there is strain produced in it when stress is applied. The larger strain means the material is less elastic.