Final answer:
The primary purpose of a spreader bar is to spread weight evenly during the lifting process, ensuring stability and safety. Spreader bars are commonly made from metal due to metals' high tensile strength, ductility, and toughness, making them suitable for the stresses involved in lifting heavy loads.
Step-by-step explanation:
The purpose of a spreader bar is to spread weight evenly when lifting heavy loads. This tool is used in conjunction with cranes or lifts to ensure that the weight of a load is distributed properly, which allows for a more stable and secure lift. It is crucial when lifting objects that are large, awkwardly shaped, or require rigging points that are spread out over a larger area. Spreader bars are often made of metal, as metals have desirable properties such as strength, durability, and the ability to withstand the stresses of lifting heavy objects without deforming.
When considering why metal is used for making objects like spreader bars, it becomes apparent that the specific properties of metals make them ideal materials for such applications. Metals are known for their high tensile strength, meaning they can withstand a great deal of tension or pulling force without breaking. They also have good ductility, which allows them to be shaped without cracking, and good toughness, which enables them to absorb energy and bear sudden shocks without fracturing.