Whatever people think of the noise, I guess they like being near to a tube station and apparently there's going to be one beforethe Olympics.
Thanks for all the feedback,folks.
Whatever people think of the noise, I guess they like being near to a tube station and apparently there's going to be one beforethe Olympics.
Thanks for all the feedback,folks.
The message from Guy King contains these words:
Cor, what a splendid typo. That's two this week.
Watch the rails on ay track as a train passes over, The go up and down as the wheel weight passes over.
THAT is what is transmitted.
The earth is like a jelly. It transmits low frequencies very well.
Umm, a jelly doesn't transmit low frequencies very well. The earth is more solid than colloidal and it does transmit low frequencies well, just as a steel bar will transmit low frequencies well.
YES! You might only be 44 but you're still very handsome, witty, charming ...
Sorry
Well, Guy, I'd be happy to look after anything for such a pal!
Mary who has been 114 since our children (45, 43, 42, 40, 38) first asked. Now it's the grandchildren (21, 21, 18, 16, 13, 12, 11, 5, 2, 3 months)
Jellies resonate. So does the earth.
Two factoids, but neither relevant.
The message from "Mary Fisher" contains these words:
When I've found it and backed it up I'll get round to asking for an address to post it to.
Very relevant.
Take something that thumps the earth, and stick a spectrum analyser on a microphone some distance away, and you will see a nice resonant peak, or peaks at subsonic levels.
In fact in ares where earth tremors are frequent, extreme care is taken to ensure buildings and structures are of a different resonant frequency, or decoupled in some way.
I have a friend whose house DIRECTLY abuts a main road used by 30 ton trucks. Its literally falling down and you can feel the ground shake as they go past.
I have worked near the gold mines in Johannesburg..every time a charge went off you could feel all the building shake, for some seconds..
Low frequencies are not just transmitted by the ground, they are AMPLIFIED at some frequencies.
Take an iron bar and thump it and you will find a nice resonant peak. An iron bar is not a jelly. Hence the phenomenon of resonace does not indicate a jelly like nature of the substance that is resonating.
Hence your factoid about jellies resonating may be true but has no relevance.
But this applies even when the structure is anchored into solid rock.
Ah, use of capitals that obviously makes a factoid more correct. Oh, hang on,it doesn't. Yes, tremors transmitted by vehicles can damage buildings, ut that's another factoid.
Indeed, but that does not mean that the ground was like a jelly.
Oh, more capitals, they are not AMPLIFIED, but the tremors can be reinforced when two waves travel to the same location via different routes. Each wave is attenuated by transmission, but the peaks may reinforce causing a greater displacement at some points where the peaks are in phase and a lesser displacement where they are anti-phase. This is not amplification, but interference.
Soil is not like a jelly, with the possibly exception of incredibly wet soils such as peat bogs. Soil tends to be a dilatant suspension, rather like a mixture of starch grains with a small amount of water. The properties of soil are that it will move under a moderate pressure and tend not to move when subject to a sufficiently great compression (this is dilatant behaviour, effectively the opposite of thixotropic substances).
Soil will also liquefy if subject to vibration and this phenomenon is responsible for earthquake damage in many regions of the world. Shaking causes the liquid in the soil to lubricate the sand and clay particles and causes liquefaction that can see landslip and also can cause entire buildings to submerge.
However the nature of these soils damps (attenuates) the transmission of waves rather than amplifying them.
The longer distance transmission by "P" waves depends upon rock being a solid like steel rather than a jelly. The solid nature of rock means that these waves travel rapidly compared to "S" waves, and it is the "P" wave that is detected at distance.
Just mail me!
Mrary
The message from "Mary Fisher" contains these words:
Bloody DVD burner's gone on strike! I'll the use the boy's when he's not in bed allegedly asleep. Mine's started waggling its tray in and out at odd moments and refusing to open on command and fails to see any discs inserted. Bother.
I think it's a variation of Sod's Law - or is it Muyrphy's Law ... I confuse the two.
Mary
Considering:
Philip
James wrote:
The message from " snipped-for-privacy@gmail.com" contains these words:
"I'm not saying our tunnelling hasn't caused the wells to collapse but the tunnel is safe."
Oh, that's alright then - the tunnel's safe. Sod the poor bloody residents!
HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.