Question

a) Define elasticity of a matter. 1 b) Define stress and strain. Explain different types of stress and strain. 1+4 c) The radius of a silver bar is 30 𝑐𝑚. What force is required to stretch the bar by 12.7% of its length where Young’s modulus is 𝑌 = 7.25 × 1010 𝑁𝑚−2 . 

Answer 1

a) Elasticity is a property of matter to recover its shape after deformation.

b) Stress is what a material experiences when the force is applied, strain is the relative change in length.

c) The force is

$$F=\sigma A=\epsilon E\pi r^2=2.6\text{ kN}.$$