A sample of metal is put under a force that rises to a maximum value and then falls again to zero. The force-extension graph for the sample is shown. As the sample shortens, it follows the same force-extension curve as when it was being stretched. What is the behaviour of the metal between X and Y?
- Aboth elastic and plastic
- Bnot elastic and not plastic
- Celastic but not plastic
- Dplastic but not elastic