Alpha is often used in physics and chemistry as a symbol or in the names of things, for example alpha particles (which are two protons and two neutrons bound together into a particle the same as a helium nucleus). The symbol is also used a lot in mathematics in algebra, for example naming angles.
Recurve bow. A recurve bow is a bow with limbs that curve away from the archer when unstrung. A recurve bow stores more energy and delivers energy more efficiently than the equivalent straight-limbed bow, giving a greater amount of energy and speed to the arrow.
The use of the bow and arrow for hunting and for war dates back to the Paleolithic period in Africa, Asia, and Europe. It was widely used in ancient Egypt, Mesopotamia, Persia, the Americas, and Europe until the introduction of gunpowder.Arrowheads were first made of burnt wood, then stone or bone, and then metals. recurved bow consists of three partsâtwo flexible limbs extending from opposite ends of a rigid riser. The bow's total length may be 50-70 in (125-175 cm). The riser, which is about 20 in (50 cm) long, provides a comfortable handgrip and a ledge on which the arrow rests prior to release.