Heat (4 Viewers)

[ann post]

*faster isn't louder, but its gotta be something-er?

 

[seanc]

Doppler effect? There's just more noise from everywhere hitting you at once?

 

[Denny Oubidoux]

Lovely swim this evening, marred only by the presence of groups of young people enjoying themselves.

 

[Space]

Doppler effect? There's just more noise from everywhere hitting you at once?

Doppler effect is the phenomenon of sound getting higher in pitch as the source of the sound approaches you and lower in pitch as it moves away.

 

[seanc]

Yeah I was worried writing that post. I'm out of my depth here compared to you guys. Isn't it because a noisy thing (an ambulance siren) is moving towards you and your hearing a sound from two different points, at the same time?

But sometimes noise stops, it starts again. And then all the noise hits you faster, because it's hot, and so it seems louder? At least in the initial instant. And there's lots of other noise happening in the example given, so it's more cacophonous, if not objectively louder.

 

[ann post]

Doppler effect is someone with a slinky that you are holding the other end of walk towards or away from you. The slinks per metre increase the pitch goes up, the slinks per metre decrease, the pitch goes down.

JCB is big long waves - these things are gonna between a few metres long to a metre long at high amplitude (the waves are very tall). Like the tearing the earth will probably be doing crazy 1-15hz stuff - this is more 'heard' through the skeleton than the ear. Like physically JCB sound waves would be surfable potentialy.

I think you are on the right track with reflections though just the terminology is all over the place with sound.

Concrete is just about the worst material for reflecting sound, and i also what building sites are made of - so you could be in a postion where you are consisitently hearing the same small range of sounds, and thier relections or refractions which are going to be close dischordants for hours, its going to feel louder because of how much it is tiring your ears. They are travelling fast so relecting possibly 10% more than normal sound energy. A bad sound environment made a few % worse.

 

[magicbastarder]

Concrete is just about the worst material for reflecting sound

of course, when ap says worst, he means best.

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[ann post]

This is true.

 

[flashback]

I was curious - Mean we could be talking about 10 degrees in a winter shift, and 30 today, so the sound is hitting you faster by up to 12m/s

(Thats 43kmh faster)

View attachment 14999

man. Physics is hard.

I'd have thought the exact opposite.
Sound travels slowly in gas, faster in water, and faster again through solids. Like, you notice that when you're underwater, sound seems to travel almost instantly, also you can't tell where it's coming from because the delta between it arriving in one ear then the other is so small your brain can't do that calculation.

Soooo, I just went: speed of sound is proportional to density of the medium. Things get less dense when they get hot, so I'd guess the speed of sound decreases the warmer it gets.

Completely wrong.

He's saying you put more energy into the gas, the molecules jiggle about more, which results in the gas being less compressible (right?), which results in sound moving faster through it.

So therefore the higher the pressure of the gas the faster sound moves through it. Also the more humid it would be, the more water knocking around, the less compressible the air is, the faster sound travels too.

Has to be. Right?

 

[JohnnyRaz]

*faster isn't louder, but its gotta be something-er?

higher pitched?

 

[magicbastarder]

man. Physics is hard.

one of the more counterintuitive physics concepts which you'd experience in everyday life has to be that warm water is better at dissolving solids but worse at dissolving gases.

 

[flashback]

one of the more counterintuitive physics concepts which you'd experience in everyday life has to be that warm water is better at dissolving solids but worse at dissolving gases.

Here, have you ever noticed when you're stirring your coffee and it's all in a whirlpool, if you tap the center of the cup the pitch of taps of the cup changes as the whirlpool dissipates?

I think I have.

 

[ann post]

higher pitched?

Nope.

wave frequency = pitch in Hz
wave amplitude = volume
speed in this case is how fast it gets from A to B through the medium (air).
Like using an electric kitchen knife to cut air or to cut hard bread, the knife still has the same frequency and amplitude.

 

[Space]

Nope.

wave frequency = pitch in Hz
wave amplitude = volume
speed in this case is how fast it gets from A to B through the medium (air).
Like using an electric kitchen knife to cut air or to cut hard bread, the knife still has the same frequency and amplitude.

You've ignored friction in your example there.

 

[therealjohnny]

for the love of fuck lads!!

 

[Space]

for the love of fuck lads!!

For the love of physics and sound Johnny.

 

[JohnnyRaz]

Nope.

wave frequency = pitch in Hz
wave amplitude = volume
speed in this case is how fast it gets from A to B through the medium (air).
Like using an electric kitchen knife to cut air or to cut hard bread, the knife still has the same frequency and amplitude.

but if a wave is moving faster that changes its frequency (ie cycles per second?)?

 

[Space]

but if a wave is moving faster that changes its frequency (ie cycles per second?)?

Speed of sound doesn't change the frequency.

 

[ann post]

for the love of fuck lads!!

I love this shit

Meanwhile

@ernesto on day 2 beside a JCB reads phone, throws it into building waste pond

 

[magicbastarder]

but if a wave is moving faster that changes its frequency (ie cycles per second?)?

The source is still vibrating at whatever frequency it's vibrating at.