The speed of sound in air at 20 °C is approximately 343 m/s. Using the wave equation v = fλ, where v is velocity and f is frequency, we calculate λ = 343 / 20,000, which equals 0.01715 meters, or approximately 1.7 × 10^-2 meters.

Sound travels fastest in solids because the particles in a solid are more closely packed and have stronger intermolecular forces compared to liquids and gases. This allows the mechanical vibrations to be transmitted more efficiently and rapidly between adjacent atoms.

The speed of sound is determined by the mechanical properties of the medium, specifically its elasticity and density. Sound travels fastest in solids, slower in liquids, and slowest in gases because the intermolecular forces and density vary significantly between these states of matter.