In physics, energy is the quantitative property that must be transferred to an object in order to perform work on, or to heat, the object. Energy is a conserved quantity; the law of conservation of energy states that energy can be converted in form, but not created or destroyed.
The speed of a sound wave depends upon the medium through which it travels. In general, sound travels faster through solids than through liquids or gases. Also, the denser the medium, the slower sound will travel through it. The same sound will travel at a different speed on a cold day than it would on a warm day.
Stone tools we’re first used around 3,300 BCE