Question

3. c) A wire of length 7 m and radius 2.37 mm is stretched by a load of 12370 gm and increased by 1.78% of the original length. Find the stress, strain, and Young's modulus of the material of the wire.

Answer 1

Find the stress:

$$\sigma=\frac{F}{A}=\frac {mg}{\pi r^2}=6.87\text{ MPa}.$$

The strain:

$$\epsilon=1.78/100=0.0178.$$

Young's modulus of the material:

$$E=\frac{\sigma}{\epsilon}=386\text{ MPa}.$$