Speed of sound activity - Measure the echo - Homemade Science with Bruce Yeany

The speed of sound can be measured with reasonable results by measuring the time of an echo. A couple blocks of wood for clapping together, a stopwatch, and a calculator are the equipment was used for the middle school classroom activity.

[hasibjoy]

Hope I had a teacher like you during my high school. Hope every children wold have a teacher like you. God bless you sir.

[thesecondphoenix]

1:40 bottom left corner, the kid on the bike noticed what was going on and slowly rode off screen.

[bitkefka]

Teachers like you sir are why I fell in love with Math and Science. Keep up the good work.

[magpiestudent]

This is the best example of this experiment on Youtube! Love it. You seem like a great teacher.

[kallewirsch]

This reminds me on an experiment I did, when I was 16 or 17, nearly 40 years ago. Back in those days, airplanes were not that common in Europe in every spot and in the small village I lived, road traffic noise was not a problem. When looking up, I noticed that I could make out a narrow spot, where the noise generated from an airplane seems to emit. Of course this spot was way behind the actual plane and moves in the same path. When a plane flew (more or less) above my head a took a measurement of how long it took that 'noise spot' to reach the same position. Assuming an average speed of sound I then was able to calculate the height of that plane and by measuring the angle the plane has moved since then, I also calculated the plane velocity. Well, the numbers were of course not accurate, by seemed to be in a plausible range.

[asmoth]

Actually there was a simple way to measure the echo with a greater precision. You could :
- Either extract the sound from your video, or simply record the sound using a microphone only
- Visualize the sound waveform of the audio file in a software like Audacity, zoom in and see the exact time of the first clap, and of the echo, and measure the difference.
I guess you can have a really great precision by proceeding this way, providing the different sounds are distinct and loud enough to see exactly when they happen in the waveform.

Anyway that was a cool video, and it was a good thing you put your measurements into perspective at the end, by showing what could be improved in your protocol :)

[Bibibosh]

i like you and your "activities" so schooly ! your the best teacher

[thatrandomcuber]

I am watching this for my assessment thanks for the advice bruce 👍

[AlfilKamikaze]

Hey Bruce. It also can be the wind. You might be not hearing the "sound" that hit straight forward from the building. Just a guess. You can make the circle inside the square to measure it.

[dimkk]

Nice work team!
Excellent teacher! We need more like him! 👏🏻👏🏻👏🏻

[El_EspaciodeCesar]

Very good practice profe, another easy way is to explode a firecracker and record video 200 or 300 meters away, then count the frames between the flash of light and the sound recorded in the audio track.
Greetings from Argentina

[BENBASIL]

You seem like such an awesome teacher! I wish I was taught by someone as passionate as you in high school

[jonesscotta]

Well done Bruce! Repeat the experiment in the Summer or Winter.

[calinbaciu]

Speed of sound vary with humidity.
Very Very good professor! Well done. Keep doing this good stuff. Congratulation!

[jadkins]

Really wish I had a teacher like you when I was in school.

[sabriath]

Another way to do your class into 2 groups of equal students, all of them have the same timer device. Group A will stand on one side of the football field, Group B will stand on the other side. You let your children know before the experiment that you will tap the blocks 3 times to begin student will be given a number to listen for (so 4 and up). Each group will have a student listening for the same number, they will be considered "sync partners." The MOMENT the student hears the clap of their number, they will start their timer. When all the claps are done, have both groups meet in the middle, and you will tell them to stop their timers on a count of 3 all together.

Sync partners will subtract their times to get the differential can calculate the speed of sound, no need to listen for echoes. The neat part about this experiment, you don't have to stand in the same place as the other students even more fun if you give them a triangulation problem to solve.

[gonchitoakash]

Amazing way to teach, lucky students!

[cookie_licker]

these videos are Always really interesting to watch

[aszi]

I would just record the sound and find the time in an audio player/editor like Audacity.

[KitBetts-Masters]

great video Bruce. I'd love to try it with our younger students... now i just need to find a place at school with a long distance and an echo!