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.
Make sure the ball of your foot lines up with the the ball of the boot (that's the widest part of the boot where the steel shank ends). If the boot is too short, your toes will be forced into the toe box. Boots should slip slightly in the heel.