Speed of Sound
Speed of sound refers to “how fast sound waves travel through a medium, such as air, liquids, or solids”.
Measuring the Speed of Sound
There are direct methods available to measure the speed of sound. Two common experimental methods are:
– Method 1 : Measuring Between Two Points
– Method 2: Using Echoes
Method 1: Measuring Between Two Points
- Two people stand about 100 meters apart. The distance is measured with a trundle wheel.
- One person creates a sharp sound by banging two wooden blocks together above their head.
- The second person uses a stopwatch and starts timing upon hearing the sound, stopping after 20 sounds.
- The experiment is repeated for accuracy and an average time is calculated.
- Speed of sound is calculated using: \text{Speed of sound} = \frac{\text{Distance traveled by sound}}{\text{Time taken}}
Method 2: Using Echoes
- A person stands about 50 meters from a wall or cliff; the distance is measured with a trundle wheel.
- They clap two wooden blocks together and listen for the echo.
- Clapping is repeated in rhythm with the echoes.
- A second person starts a stopwatch upon hearing a clap, stopping after 20 claps.
- The average time is calculated over several trials.
- The distance sound travels between each clap and echo is double the measured distance.
- Over 20 claps, total distance is computed as : 20×2×distance
- Speed of sound is found using: Speed of sound=\text{Speed of sound} = \frac{2 \times \text{Distance to the wall}}{\text{Time taken}}
Speed of Sound in Different Mediums
Sound travels at different speeds in solids, liquids, and gases.
It moves fastest in solids, slower in liquids, and slowest in gases, due to differences in particle spacing and density.
Formula for Speed of Sound
Speed = distance / time
v = λ / T
where:
- v is the speed of sound,
- λ is the wavelength,
- T is the time period.
Since frequency f=1/T
v=λf
These formulas describe how sound travels in different media and under various conditions.