Science gurus please help music teacher

[twentypence]

Question from child

"So if you went into a room with a oxygen tank and then removed the air from the room and played a drum would it make a noise?"

As I had just tricked them into saying ds's 1/10th size cello would play higher than a full size one, by first showing a flute and a piccolo, I feel I need a full and complete answer for this one...

[tortoiseSHELL]

No, sound can't be heard in a vacuum as their are no particles to carry the wave form. So you wouldn't hear the drum.

[tortoiseSHELL]

(PS as one muso to another, what is the reason that a small cello isn't higher? I should know this but don't!)

[Slouchy]

I'm not 100% sure of this but I believe sound can't travel through a vacuum, so the answer is no.

I think.

(Not a Science guru, as you may have guessed!)

[juuule]

This any use to you?

[twentypence]

Strings are same thickness, same as a grand piano and a tiny upright.

Whereas with a piccolo and flute it's the air inside that's important.

[twentypence]

Love the bit about "when there is a battle in outer space you could see the explosions, but not hear them", I think as the battles are imaginary we will allow a further suspension of disbelief.

Thrilling that this was solved in 1660, by a combination of my ds and the surname of the boy who asked the question! Spooky.

[IorekByrnison]

I'm still confused about the cello. If you have two strings of the same thickness and tension but one is half the length of the other, surely the shorter one will sound an octave higher? Is the tension of the strings lower on the smaller instruments?

[snorkle]

twentypence, I'm not sure about the string thickness being the same on small cellos - I'm fairly sure it's advances in string technology that enables you to get low pitches on short string lengths. It's worth noting that a 1/10th cello is actually a lot bigger that 1/10th of a full size one as well. Very tiny cellists sometimes start on a viola with a spike added and these instruments do sound an octave higher.

[MrsJohnCusack]

oooooh that is spooky
Well, I've learny something today - thanks all

[MrVibrating]

Three things determine the pitch of a string:

Length - the smaller the instrument, the shorter the length and so the higher the pitch

Tension - the tighter the string, the higher the pitch

Linear density - the heavier the string, the lower the pitch

So on a smaller sized instrument, to keep the pitch the same the strings are made heavier by winding with heavier wire as much as possible. Using heavier wire means that the string doesn't have to be much thicker or tuned much looser than on a full scale length instrument, both of which have an impact on tone and the 'feel' of the instrument.

For a more detailed explanation see here or here for a bit more science

(Note: not a 'cellist but a guitarist and a scientist )

[popsycal]

no

[popsycal]

A couple of things I tell kids to rememver about pitch

Eg the shorter, narrower the string/vibrating object the higher the pitch - get them to remember it by thinking opf a tiny mouse and a huge elephant
high pitch/low pitch little/big

also I tell my class that I often think of sending them to outer space as then they could be as loud as they want and I couldn't hear a thing
I say it to ds1 often too

[popsycal]

the thing about tightening strings.......we ppicture a little mouse being stretched and his squeaks getting higer and higher

oh science is such good fun chez popsycal

[twentypence]

His strings couldn't be thicker because they would then be impossible to press down with tiny fingers. They are not under a lot of tension though - tuning is very hard because the tiniest of turns can make the pitch go up a tone even on the fine tuners.

If he presses on hard with the bow, he can get a whole other note!

Like the idea of sending the children into space!

[Blandmum]

No you wouldn't hear a sound diatnt from the instrument, as sound needs an atmoshere to travel in. However you would be dead if tyhere was no atmoshere in there, so it is a moor point any way!

If you filed the area with helium the pitch would =change because the speed of vibration of the drum/strings, would change and get faster, so the pitch would rise.

The fater the vibration the higher the pitch.

this is why you sound like Mickey mouse if you inhale helium, your vocal cords vibrate faster

[twentypence]

I just loved that he thought to take an oxygen mask into the room with him.

Would having a vacuum affect his tank though?

[snorkle]

A solid oxygen tank would withstand the (lack of) pressure OK I would think, but his body wouldn't - he'd explode unless wearing a spacesuit.

[MrVibrating]

No he wouldn't explode, although his lungs would probably rupture if he tried to use the oxygen tank.

[snorkle]

So in the scenario described the lungs would explode then.

[snorkle]

So in the scenario described the lungs would explode then.

[MrVibrating]

This is getting somewhat off topic, and I suppose it all depends what you understand from the word 'explode', but as the injury would be internal the word rupture is more appropriate IMHO.

[IorekByrnison]

I love this thread

[twentypence]

9 year old boys live off topic - I need all this info - keep going.

[MrVibrating]

What else would you like ?

[twentypence]

All this talk of explosions, rupture, what would happen if...