Which makes better packing material: a high density or low density material? Why?

Low-density items make better packing materials.

Solids with low density, such as cork or foam, are often used as cushioning material. Low density means there are relatively large spaces between atoms. That means materials may be compressed relatively easily, which is why foam and other low-density substances make good packing materials.

Polyethylene is an extremely diverse packaging material. Polyethylene can be soft and stretchy, or hard and strong.

The density and liquidity of the polyethylene is determined during the production process, which determines what type of applications it will be used for. Factories use the polyethylene pellets to make plastic bags using large machines that heat the plastic and create a tubular shape from which bags are formed.

Density is a property of material independent of quantity or shape. For example, a steel nail and a steel cube have different amounts of matter and therefore different masses. They also have different volumes.

However, if you calculate density by dividing mass by volume, the result is the same for both the nail and the cube.

For further reading, see BickfordScience.com's Chapter 4 Density and Buoyancy.

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