Explain why the shape of the product possibility frontier is bow shaped
The shape of the production possibility frontier (PPF) is bow-shaped because of the concept of diminishing returns. As resources are reallocated from one good to another along the PPF, the opportunity cost of producing an additional unit of the second good increases. This happens because resources are typically better suited to producing one type of good than another, and thus have diminishing returns when used for the less-efficient production of the second good.
In other words, as more resources are used to produce one good, the resources that are best suited for that good are used first, resulting in the initial increase in production being relatively efficient. However, as more resources are allocated to the production of that good, resources that are less well-suited for that good are used, leading to diminishing returns and a less efficient allocation of resources.
This results in the bow-shaped curve of the PPF, as the opportunity cost of producing additional units of one good increases as more resources are reallocated from the production of the other good.