How fast does sound travel through the air? You can measure it the same way you time a runner on a track. All you need is a stopwatch and a wall that produces a good echo.
You stand a known distance from a large flat surface. Fire a starter's pistol and start the stopwatch at the same moment. Stop the watch when you hear the echo. Divide twice the distance by the time to get the speed.
At room temperature you should get about 344 meters per second. At freezing the speed drops to about 331 meters per second. Sound also travels much faster through water at roughly 1480 meters per second.
Hypothesis
The hypothesis is that the speed of sound can be measured using a stopwatch and a known distance.
Sound waves travel through air at a measurable speed — and you can time them the same way you time a runner on a track. Fire a starter's pistol while starting a stopwatch, then stop the watch the moment the echo returns from a wall a known distance away. Divide twice the distance by the time, and you get the speed. At room temperature, that works out to about 344 meters per second. At freezing, the speed drops to around 331 meters per second. Through water, sound moves far faster — roughly 1480 meters per second.
You can measure how fast a shout travels the same way you time a runner on a track. Stand a known distance from a large flat surface, fire a starter's pistol, and start a stopwatch at the same moment. When the echo returns, stop the watch and divide twice the distance by the time. At room temperature you should get about 344 meters per second. At freezing, the speed drops to about 331 meters per second — a measurable change from a simple drop in temperature.
Method & Materials
You will measure the speed of sound by firing a starter's pistol and starting a stopwatch, then stopping the watch when you hear the echo.
You will need a starter's pistol, a stopwatch, and a known distance.
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The results of this experiment show that the speed of sound at 21 degrees Celsius (70°F) is 344 meters per second, or 1129 ft per second. At freezing, the numbers are 331 m/s or 1087 ft/s. There is about a 0.1% change per degree Fahrenheit. The speed of sound in water is 1480 m/s or 4856 ft/s, which is more than 3000 miles per hour.
Why do this project?
This science project is interesting because it allows you to measure the speed of sound, which is something that is usually taken for granted.
Also Consider
Experiment variations to consider include measuring the speed of sound in different temperatures and measuring the speed of sound in different mediums (such as air, water, or a vacuum).
Full project details
Additional information and source material for this project are available below.
