Soundwaves cannon group

projects: we initially started with various ideas, than selected which were doable and which weren’t, until we were left with a final idea to follow.

Project 1: using multiple sound sources, and knowing the phenomenon of waves interference, create areas where constructive interferences make the sound very powerful and audible my someone who walks in that areas, and areas where thanks to distructive interferences someone who walks there can’t hear anything

pros: really interesting for whoever walks in

cons: this would be really cool but the walls or anything in the room would make the nound waves bounce and the original idea wouldn’t work, so we need to insulate the whole room everytime or we need a specific room and than the project wuoldn’t be movable

realising that the walls of any room would interfere everytime, we decided to think smaller, and demonstrate the effects of interferences of waves not by hearing, but in a different way.(if we need a small area where we need only the waves produced by our sond sources, its easier to insulate that area)

Project 2: we found on the internet an interesting experiment that used used water and sound:

water goes down a small tube that passes in front of a speaker, and the frequence of the sound produced by the speaker affects the falling water

At different frequences the water semeed to “freeze” mid-air, or it looked like it started flowing backward against gravity

Big con: the wonderful visual effect is gained only thanks to a videocamera with a frame rate close to the frequence of the sound

Project 3: using some material (like sand or polystyrene) that is affected of different waves we want to be able to”see” the waves

searching on the internet we found uot that the thing we are thinking of already exist, and it’s called Kundt’s tube

But we want to try something new: the “normal” Kundt’s tube is made by a transparent tube with a sound source at one end and a moving piston or something similar that can shorten o extend the length of the tube

This moving end is needed becuase the powder will start to move only when the tube is at resonance

We want to show the waves, but also we want to show the phenomenon of waves interferences, so we want to put a second sound source on the moving end, so when using the apparatus you can see 3 different waves: one with the first speker on, one with the second speaker on, and one with both speakers on, where the constructive and destructive interferences create a wave much different than the other two waves

In the end we have chosen the third idea.

Materials needed:

2 speakers
trasparent tube
fine powder
piston like contraption

1) we at school already have 2 speakers, the 2 that were used by MIT professors the past year to show the properties of non-newtonian fluids, and to show how a laser that its a mirror ona sping attached to a speaker behaves: we still don’t know how did they controlled with the phone these speakers, sowe will ask them to explain to us how they did it

2) we need a trasparent tube that fits on the bigger speaker and can be closed by the other speaker that will be movable. Depending on the dimensions of this tube we could need to adapt the smaller speaker to perfectly close the tube, maybe with a ring of the same material of the tube.

3) The fine powder is the easy part: in theory it only needs to be a fine and light powder, and we will try with chalk powder(thats easy to obtain in a school). In alternative, small pellets of polystyrene cold be used

4) The piston like contraption needs to be steady and easy to use and calibrate (at the moment we are thinking of simpy glueing a stick to the back of the little speaker and move it manually until you find the right spot) we still need to think about and test many things, like trying if the little speaker would work as the closing end of the tube, and also getting the speakers to work we are also thinking of changing the name of the project, the “cannon” part doesn’t fit in with the project anymore.