Question

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

The strain of 12.7%, or 0.127, is what we will use to solve the problem:

$$\epsilon=\frac{\sigma}{E}=\frac{F}{AE},\\\space\\ F=\epsilon AE=\epsilon·\pi r^2·E,\\\space\\ F=2.6\text{ MN}.$$