It was a lovely sunny day on which to do a very large experiment. Finding the speed of sound.
We needed a large distance so we went to the Nevill field
Speed = Distance / Time so we need to measure the distance.
This was done with a trundle wheel
and a lot of counting!
We checked it a few times
to make sure the result was reliable
as there are a lot of clicks to count
and the listeners kept moving (but not much).
We put our sound source at the other end of the long distance
The clapper board was used to make a loud bang
We can see the boards crashing together and that's when we started the timers
Then we stopped the timers when we heard the sound a fraction of a second later
and wrote the times down
We did this many times so we could try to rule out any errors
We changed jobs too so everyone got to experience seeing the clapper crash shut before hearing the bang a moment later.
This is why you see the runners start a moment before you hear the starting pistol when you are by the finish line on Sports Day. Also why the bat seems to hit the ball before you hear it when you are watching cricket on the boundary. Fireworks do the same, flash of light before you hear the big bang and its why if you look at where the sound is coming from you wont see the aircraft that's making it. The plane will be further ahead well in front of its sound.
We have all of the data now so next lesson we will have to do some calculations and see if we have an accurate result.
