The speed of sound depends on the medium that the waves pass through, and is a fundamental property of the material. The first significant effort towards the measure of the speed of sound was made by Newton.
When the Occupational Safety and Health Act passed in 1970, steel-toe boots became a standard in the American workplace, preventing thousands of on-the-job injuries. Today's technology has only increased the variety of work boots available, and it's important to understand the differences before purchasing a pair.
Composite toe boots are lighter than steel toe boots and do not contain any form of metals in them. Instead, they contain a composite material in the toe portion of the boots. Composite materials include, but are not limited to, Kevlar, plastic, and carbon fiber.