Sound

• Sound travels faster through solids than liquids, which travel faster than gases.
• The speed of sound is the distance travelled by sound waves per unit time.
• Increasing the density of air or water will increase the speed of sound.
• The speed of sound is affected by temperature - it increases with increasing temperature.
• Decreasing the density of air or water will decrease the speed of sound.
• In air at room temperature (20°C), the speed of sound is approximately 340 m/s or 1125 km/h.
• The speed of sound increases with increasing temperature due to increased particle vibrations.
• At sea level, the speed of sound is around 768 miles per hour (mph) or 343 meters per second (m/s).
• The speed of sound increases with increasing frequency.
• The speed of sound can be measured using an echo sounder.
• Sound waves are longitudinal waves that require a medium to travel through.
• Sound waves can travel through solids, liquids, gases, and vacuum.
• Solids have the highest propagation velocity compared to other states of matter.
• Liquid has lower propagation velocity than solid but higher than gas.
• Gas has the lowest propagation velocity among all three states of matter.
• Decreasing the temperature of air or water will decrease the speed of sound.
• In water at 20°C, the speed of sound is about 1500 m/s.
• When sound passes from one medium to another, some of its energy is reflected back into the original medium as an echo.
• Compressions occur when particles are pushed together, while rarefactions occur when particles move apart.
• Longitudinal waves have compressions and rarefactions.