Question

1. 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 x 10¹0 Nm-².

Answer 1

The strain is 12.7%, or 0.127, which can be expressed as:

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