Things you always wanted to know the answer to [Vol. 3]

Things you always wanted to know the answer to [Vol. 3]

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MartG

20,624 posts

203 months

Wednesday 17th May 2017
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Dr Jekyll said:
Apparently time dilation has been demonstrated on a small scale via clocks in spacecraft but the same problem arises. Is it the acceleration that's causing the dilation in this case?
No - just the relative velocity. It's why the clocks aboard certain satellites e.g. GPS have to be continually updated

ambuletz

10,692 posts

180 months

Thursday 18th May 2017
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hypothetically speaking if you travelled to another country (or came back to this one) and you was over the limit on how much alcohol you could bring (lets say you brough 1 bottle of vodka too many), would you be allowed to have a chug of the excess bottle before they confiscate it?

do they take all bottles? ive always stayed within the limit.

Halmyre

11,148 posts

138 months

Thursday 18th May 2017
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MartG said:
Dr Jekyll said:
Apparently time dilation has been demonstrated on a small scale via clocks in spacecraft but the same problem arises. Is it the acceleration that's causing the dilation in this case?
No - just the relative velocity. It's why the clocks aboard certain satellites e.g. GPS have to be continually updated
The error in GPS satellites is actually due to their orbital height - it makes them run fast from our POV (as per general relativity). Their motion will make them run slow (as per special relativity) but not enough to offset the other error.

dci

528 posts

140 months

Thursday 18th May 2017
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Pommygranite said:
In commercial/industrial fire extinguisher systems there is a little glass vial of liquid above the pipe and the glass it to break in the event of a fire - what's the liquid?
I'm not sure on the name of the liquid (possibly the same liquid that's used in non mercury thermometers?) but the glass vial holds a stopper in place which in turn holds back pressurised water, gas or sometimes air.

When subjected to heat the liquid expands breaking the vial and releasing the water to extinguish the fire. Somewhere inline on that pipe will be a flow switch to start up the water pumps or release a gas extinguishing agent. The colour of the liquid dictates the temperature at which the vial will break such as red for 65 degrees, blue for 85 degrees etc..

It's a common movie mistake that smoke will set off a sprinkler and that all sprinklers will be set off simultaneously. They react locally to heat sources, 99% of the time anyway..

Edited by dci on Thursday 18th May 22:44

Shakermaker

11,317 posts

99 months

Friday 19th May 2017
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ambuletz said:
hypothetically speaking if you travelled to another country (or came back to this one) and you was over the limit on how much alcohol you could bring (lets say you brough 1 bottle of vodka too many), would you be allowed to have a chug of the excess bottle before they confiscate it?

do they take all bottles? ive always stayed within the limit.
They take it all. yes. I would be surprised to watch them take you to town over "one bottle too many" of Vodka. They could ask you to pay the duty but if you refused you'd lose it all.

But I have seen many many people lose entire suitcases filled with cigarettes, which are far more common for people to try and sneak in because of the much bigger price difference in them, especially from places like Tenerife.

Ayahuasca

27,427 posts

278 months

Friday 19th May 2017
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I saw a video on FB of a cyclist on a down-hill stretch of road. He took his feet of the pedals and lay horizontally on the bike with his legs pointed straight out behind him. The idea was to reduce drag. The clip went on to show him in this low-drag mode (not pedaling, just coasting) overtaking cyclists who were in the conventional pose who were pedaling down the hill.

How realistic is is that all of the power (and more) of the pedaling cyclists is used up overcoming the difference in drag between a vertical and a horizontal rider?


droopsnoot

11,815 posts

241 months

Friday 19th May 2017
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Ayahuasca said:
I saw a video on FB of a cyclist on a down-hill stretch of road. He took his feet of the pedals and lay horizontally on the bike with his legs pointed straight out behind him. The idea was to reduce drag. The clip went on to show him in this low-drag mode (not pedaling, just coasting) overtaking cyclists who were in the conventional pose who were pedaling down the hill.

How realistic is is that all of the power (and more) of the pedaling cyclists is used up overcoming the difference in drag between a vertical and a horizontal rider?
And, how much will it hurt when he inevitably hits a problem in the road surface and goes a over t? The thought of riding like that invokes something in me, something like when I think back to riding no-handed down a local hill, or climbing a really tall ladder. Aargh.

Ayahuasca

27,427 posts

278 months

Friday 19th May 2017
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droopsnoot said:
Ayahuasca said:
I saw a video on FB of a cyclist on a down-hill stretch of road. He took his feet of the pedals and lay horizontally on the bike with his legs pointed straight out behind him. The idea was to reduce drag. The clip went on to show him in this low-drag mode (not pedaling, just coasting) overtaking cyclists who were in the conventional pose who were pedaling down the hill.

How realistic is is that all of the power (and more) of the pedaling cyclists is used up overcoming the difference in drag between a vertical and a horizontal rider?
And, how much will it hurt when he inevitably hits a problem in the road surface and goes a over t? The thought of riding like that invokes something in me, something like when I think back to riding no-handed down a local hill, or climbing a really tall ladder. Aargh.
Found the clip:

https://www.youtube.com/watch?v=bvmibwafGXc

Drummond Baize

200 posts

94 months

Friday 19th May 2017
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Staying, if I may, with the speed of light theme;

They say that some/most of the stars we see in the night sky are probably "dead" by now, because they're so far away and the light from them takes so long to get here, right?

So have we ever witnessed the "death" of a star? Like an astronomer is peering through his telescope at Alpha Gemini Kumquat 824B and then suddenly it goes out?

MartG

20,624 posts

203 months

Friday 19th May 2017
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Drummond Baize said:
Staying, if I may, with the speed of light theme;

They say that some/most of the stars we see in the night sky are probably "dead" by now, because they're so far away and the light from them takes so long to get here, right?

So have we ever witnessed the "death" of a star? Like an astronomer is peering through his telescope at Alpha Gemini Kumquat 824B and then suddenly it goes out?
That's not how most stars end their lives - Google nova and supernova wink

Drummond Baize

200 posts

94 months

Friday 19th May 2017
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MartG said:
Drummond Baize said:
Staying, if I may, with the speed of light theme;

They say that some/most of the stars we see in the night sky are probably "dead" by now, because they're so far away and the light from them takes so long to get here, right?

So have we ever witnessed the "death" of a star? Like an astronomer is peering through his telescope at Alpha Gemini Kumquat 824B and then suddenly it goes out?
That's not how most stars end their lives - Google nova and supernova wink
But don't some just fizzle out?

Einion Yrth

19,575 posts

243 months

Friday 19th May 2017
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Drummond Baize said:
MartG said:
Drummond Baize said:
Staying, if I may, with the speed of light theme;

They say that some/most of the stars we see in the night sky are probably "dead" by now, because they're so far away and the light from them takes so long to get here, right?

So have we ever witnessed the "death" of a star? Like an astronomer is peering through his telescope at Alpha Gemini Kumquat 824B and then suddenly it goes out?
That's not how most stars end their lives - Google nova and supernova wink
But don't some just fizzle out?
Sort of

Willy Nilly

12,511 posts

166 months

Tuesday 23rd May 2017
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So, who else had to type Ariana Grande into google?

briangriffin

1,570 posts

167 months

Tuesday 23rd May 2017
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Will it ever be possible to disprove God? If aliens landed yesterday and showed that sub human at Manchester arena that there's no such thing would he believe it or does 'faith' trump proof?

MartG

20,624 posts

203 months

Tuesday 23rd May 2017
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Willy Nilly said:
So, who else had to type Ariana Grande into google?
Me


drainbrain

5,637 posts

110 months

Tuesday 23rd May 2017
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MartG said:
Willy Nilly said:
So, who else had to type Ariana Grande into google?
Me
Me too frown

lucido grigio

44,044 posts

162 months

Tuesday 23rd May 2017
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drainbrain said:
MartG said:
Willy Nilly said:
So, who else had to type Ariana Grande into google?
Me
Me too frown
Not me .I'm down with the kidz ,innit.

Although I do mix her up with Iggy Azalea.

vonuber

17,868 posts

164 months

Tuesday 23rd May 2017
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briangriffin said:
Will it ever be possible to disprove God? If aliens landed yesterday and showed that sub human at Manchester arena that there's no such thing would he believe it or does 'faith' trump proof?
Faith always beats proof, sadly.

briangriffin

1,570 posts

167 months

Tuesday 23rd May 2017
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vonuber said:
Faith always beats proof, sadly.
That was my argument in work recently, friendly debate involving deeply religious Christian who doesn't force it in us and is probably the nicest bloke I've ever met but his belief that the end of days it can't be a nuclear apoloclypse it's something caused by god suggests faith not rationale.

But I'd say my argument to anyone trying to dis[prove religion is that it's all bout faith (even though I'm an atheist) if I prove there's no god have I really disproved faith? Is it an unasnswerable question?

glazbagun

14,259 posts

196 months

Wednesday 24th May 2017
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vonuber said:
briangriffin said:
Will it ever be possible to disprove God? If aliens landed yesterday and showed that sub human at Manchester arena that there's no such thing would he believe it or does 'faith' trump proof?
Faith always beats proof, sadly.
I do think it should be fairly possible to prove llogically that an Abrahamic monotheistic God certainly dens't care about us though. If he cared favoured the Jews he didn't stop the Holocaust, if he cared about Orthodox, RC or Protestant churches he's done SFA to pick sides, if he cared about Islam he wasn't much cop against Genghis Khan, the Western powers or the Sunni/Shia conflicts over the years.

It might be impossible to prove a negative, but proving that, should he exist, he doesn't care how you live your life seems fairly straight forward.
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