Injection moulding is used to create many things such as wire spools, packaging, bottle caps, automotive parts and components, toys, pocket combs, some musical instruments (and parts of them), one-piece chairs and small tables, storage containers, mechanical parts (including gears), and most other plastic products available today. Injection moulding is the most common modern method of manufacturing plastic parts; it is ideal for producing high volumes of the same object.
When thermoplastics are molded, typically pelletised raw material is fed through a hopper into a heated barrel with a reciprocating screw. Upon entrance to the barrel, the temperature increases and the Van der Waals forces that resist relative flow of individual chains are weakened as a result of increased space between molecules at higher thermal energy states.
It has been generally accepted that the first inhabitants of North America migrated from Siberia by way of the Bering land bridge and arrived at least 12,000 years ago; however, increasing evidence suggests an even earlier arrival. After crossing the land bridge, the first Americans moved southward along the Pacific coast and through an interior ice-free corridor between the Cordilleran and Laurentide ice sheets. The Clovis culture appeared around 11,000 BC, and is considered to be an ancestor of most of the later indigenous cultures of the Americas.