Mechanical waves are the type of waves that involve the oscillation of matter. They require a material medium for propagation and thus, transfer most of their energy through this medium. While these waves cover very large distances, the movement of the medium, on the other hand, is very limited and is sometimes almost immobile. Thus, the medium of propagation hardly seems to move from its initial position of equilibrium. Mechanical waves carry bundles of energy as they move. The direction of this energy is in the direction of wave propagation. Mechanical waves can only be produced and propagated along media that have inertia and elasticity. In contrast to this, electromagnetic waves do not need any medium for propagation and can even travel in a vacuum.
, economics deals with the allocation of scarce resources in order to best maximise tool. Regarding a country the power concentrate is on its creation of all goods which is measured by its budget in world marketplaces, i. e. the amount of wealth that it creates for the country. A Production Prospects Frontier (PPF) graph (Fig 1) may be used to show the maximum creation of goods that a country can perform given its limitation of resources and current technology. A combo of goods outside of the curve, e. g. point C is extremely hard, while one under the curve (e. g. point A) means that the economy is underperforming, in other words is not using all of its resources effectively (as in the case of point B). A final point to notice from this graph is that an increase in creation of 1 good will result in a chance cost in development loss of another good.