Sound travels faster through solids than through air because of the way that sound waves interact with the molecules in the medium. Sound waves are caused by vibrations of molecules. When a sound wave travels through a solid, the molecules in the solid vibrate and transfer the energy of the sound wave to neighboring molecules. This process happens very quickly in solids, so sound waves can travel through solids very fast.

In air, the molecules are much farther apart than they are in solids. This means that it takes longer for the sound waves to transfer their energy to neighboring molecules. As a result, sound waves travel more slowly through air than through solids.

The speed of sound also depends on the temperature of the medium. Sound waves travel faster through warmer materials than through cooler materials. This is because the molecules in warmer materials are moving faster, so they can transfer the energy of the sound wave more quickly.

The speed of sound in air is about 767 miles per hour (1,235 km/h) at sea level and 20 degrees Celsius (68 degrees Fahrenheit). The speed of sound in water is about 4,900 miles per hour (7,875 km/h). The speed of sound in steel is about 15,000 miles per hour (24,140 km/h).