What keeps me up late!

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Externet
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Re: What keeps me up late!

Post by Externet » Fri Jun 30, 2017 7:08 am

Is it because the zero meridian is adopted as a line; zero latitude also a line, instead of points ?

If the zero latitude was north pole; 100 latitude south pole; will it differ from current thinking ?
Zero longitude being the crosspoint of equator and dateline...
The spinning axle of the globe is taken in account as something 'special' to divide the globe. Must it be like that ?
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Re: What keeps me up late!

Post by dyarker » Fri Jun 30, 2017 7:40 am

Oh, never mind.
Bye,
Dale Y

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MicroRem
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Re: What keeps me up late!

Post by MicroRem » Fri Jun 30, 2017 7:30 pm

If a tree falls in the forest, and a man doesn't hear it, is he still wrong?

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Re: What keeps me up late!

Post by CeaSaR » Sun Jul 02, 2017 1:08 pm

MicroRem wrote:If a tree falls in the forest, and a man doesn't hear it, is he still wrong?
Only if his wife knows of the tree's situation. :razz: :mrgreen:
Hey, what do I know?

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Re: What keeps me up late!

Post by gerty » Fri Jul 21, 2017 7:45 am

Where I used to work we built large air conditioners. Our specs for the longest read "Length 42' +- 2mm". The bad part was our inspectors were only equipped with 6" dial calipers and a calibrated 16' tape measure.
I asked an inspector once how he knew the length was ok, he said if all the covers fit ok he was good with that...

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Re: What keeps me up late!

Post by MrAl » Wed Jul 26, 2017 3:37 am

The original questions repeated with some answers...

If, you could travel faster than the speed of light, could you go somewhere, stop, turn around, and watch yourself arrive;
and, if you traveled faster than the speed of sound, would it likewise arrive after you?
Ans: Lightning travels faster than sound, so we see the light flash before we hear the thunder clap. The sound wave arrives after the light wave because sound travels slower than light. The distance to the lightning strike can be calculated this way by timing the time between the light flash and sound of the thunder clap.

If you dropped a heated sewing neeedle into the ocean, you could claim that you rasied the ocean's temperature and tide, but could you prove it?
Ans: A relatively simple problem involving specific heat capacity.

A crystal radio absorbs some of the transmitted energy during the conversion of that signal to audible energy, could enough crystal radios absorb all the energy so that nobody hears anything?
Ans: No. The radio waves disperse as they move outward, so without a very specific setup the information is available on a surface that gets larger and larger as we move away from the transmitter. The radio receiver would be very tiny compared to the surface area, unless we invoked very strict constraints about the sizes and distances involved which we normally dont do.

Do you weigh an envelope with, or without the stamp? If the stamp places it into the next weight class, do you pay more?
Ans: Yes or No, depending on who makes the decision of what stamp to use. If you do the weighing, then yes, if the post office does the weighing, then No. That's because when you do the weighing you do it before the stamp is placed on the envelope, but when they do it they get it after you already placed the stamp on it, so it weighs slightly more. If they are making the decision though then they weight it before placing the stamp, so the weight is lower. I would bet they have a tolerance though so more generally the answer would be No.

A radio is playing loudly in an adjacent room. You close the door and your room becomes quieter. Does the other room become louder?
Ans: Yes, in the simple cases. The exit represents a loss of energy when open, and when closed confines the energy.

Now let's see if that sparks anything here :???:
Ans: Yes, it did :-)
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Lenp
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Re: What keeps me up late!

Post by Lenp » Wed Jul 26, 2017 5:37 am

Hi Al... Just a few comments back...

Ans: Lightning travels faster than sound, so we see the light flash before we hear the thunder clap. The sound wave arrives after the light wave because sound travels slower than light. The distance to the lightning strike can be calculated this way by timing the time between the light flash and sound of the thunder clap.

Well, some of us lucky folks, with really sharp, and in depth perception, can hear the thunder before we see the lightning, so does that change the rules? :eek:
Does the timing go...one Mississippi, two Mississippi....three Missip....Whoa!!

------

Ans: Yes or No, depending on who makes the decision of what stamp to use. If you do the weighing, then yes, if the post office does the weighing, then No. That's because when you do the weighing you do it before the stamp is placed on the envelope, but when they do it they get it after you already placed the stamp on it, so it weighs slightly more. If they are making the decision though then they weight it before placing the stamp, so the weight is lower. I would bet they have a tolerance though so more generally the answer would be No.

A solution would be to put a dry stamp on then weigh it, but then the lick factor comes into play! It's getting too complex, I'll just email it! :shock:

------

Ans: A relatively simple problem involving specific heat capacity.

I guess that's something like my wife's old British cookery book, regarding making custard.
'Test the custard's temperature with your finger. It will be right when you put your finger into the pudding and you can count to 5. Less, it's too hot. More it's too cool' :idea:


Side kick:
Ever notice the 'soldering experts' on YouTube, they melt and smear. Probably became certified through a training session at Sam's Drywall Finishing School!

(I really do need a different hobby!)
Len

“To invent, you need a good imagination and a big pile of junk.” (T. Edison)
"I must be on the way to success since I already have the junk". (Me)

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Re: What keeps me up late!

Post by dyarker » Wed Jul 26, 2017 6:03 am

An alternate possibility on the envelope -

You put the contents inside, and suspect it might be over weight. You don't want it to come back; so either you weigh it yourself, or take it to the Post Office. With the measured weight and postal chart the correct postage is lookedup. Then stamp, or stamps, for that amount are put on.

Not as much fun as your "chicken or egg" approach, but what I do.

Til next time,
Dale Y

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Re: What keeps me up late!

Post by gerty » Thu Jul 27, 2017 6:38 am

"Side kick:
Ever notice the 'soldering experts' on YouTube, they melt and smear. Probably became certified through a training session at Sam's Drywall Finishing School!"
I've noticed that also, and when my students see it they want to know why the youtuber can do it that way, and not them.
I tell then go ahead and try it, and usually the first tug will dislodge it.

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Re: What keeps me up late!

Post by MrAl » Fri Jul 28, 2017 6:34 pm

Lenp wrote:Hi Al... Just a few comments back...

Ans: Lightning travels faster than sound, so we see the light flash before we hear the thunder clap. The sound wave arrives after the light wave because sound travels slower than light. The distance to the lightning strike can be calculated this way by timing the time between the light flash and sound of the thunder clap.

Well, some of us lucky folks, with really sharp, and in depth perception, can hear the thunder before we see the lightning, so does that change the rules? :eek:
Does the timing go...one Mississippi, two Mississippi....three Missip....Whoa!!

------

Ans: Yes or No, depending on who makes the decision of what stamp to use. If you do the weighing, then yes, if the post office does the weighing, then No. That's because when you do the weighing you do it before the stamp is placed on the envelope, but when they do it they get it after you already placed the stamp on it, so it weighs slightly more. If they are making the decision though then they weight it before placing the stamp, so the weight is lower. I would bet they have a tolerance though so more generally the answer would be No.

A solution would be to put a dry stamp on then weigh it, but then the lick factor comes into play! It's getting too complex, I'll just email it! :shock:

------

Ans: A relatively simple problem involving specific heat capacity.

I guess that's something like my wife's old British cookery book, regarding making custard.
'Test the custard's temperature with your finger. It will be right when you put your finger into the pudding and you can count to 5. Less, it's too hot. More it's too cool' :idea:


Side kick:
Ever notice the 'soldering experts' on YouTube, they melt and smear. Probably became certified through a training session at Sam's Drywall Finishing School!

(I really do need a different hobby!)

Hi Len,

I am not sure what you are trying to say about the lightening.
Sound travels much more slowly than light, so in the normal case we'll see the light before we hear the sound.
If you dont agree then you'll have to elaborate by setting up a case where your view might be valid. When we talk about logical things like this we often have to spell out the assumptions. My assumptions are only that the normal case is where the flash is maybe one or two miles or more away, and we are not blind.

As to the 'lick' factor, you've now introduced another dimension into the discussion that was not there previously. If i were allowed to do that i could disprove almost anything simply because the other party had no chance to consider that option yet.
But assume we allow this new issue, if you hurry up to the post office then it might still be wet so it might weigh even more. If you let it dry, it may weight the same depending on what you ate or drank that day and maybe the day before. There are also self sticking stamps that i use exclusively so this does not apply to me :-)
The main point was that if you weight the envelope first, then you only know the weight of the envelope, so after you put the stamp on it weights more and could break over the threshold to the next price level. A solution would be to use a numerical approach similar to some electrical problems, which would mean all we have to do is weigh both the envelope and the stamp at the same time, and if it goes over the price break point then add another stamp and that should do it because the next price point will be much higher in weight than a single stamp.
A funny idea would be to tape a nickle on the envelope or maybe two quarters. People used to do this a long time ago in a pinch. That makes it weight more and we might get into a situation where when we add a coin it keeps going to the next level (ha ha) so we end up piling on coin after coin with no end in sight, until we realize that we ran out of money and so we cant send the envelope (he he).

The hot needle in the ocean issue was solved by specific heat capacity. The temperature and mass and material of the needle hold a certain amount of energy when hot and when placed into water of a known temperature will transfer some of the heat to the water. Since it is a static problem we only have to look at final values, and that would come from the point where everything is again in equilibrium. That would mean the water is a little hotter.
Easier to start with a small beaker of water. The temperature may not increase much, but in theory it could be calculated under a reasonable set of assumptions. IF one of those is to allow cooling through surface area, then there is a chance that the whole setup will cool down to the same temperature of the air in a certain amount of time.

Each of these kinds of questions are often meant to draw attention to some fact about accuracy or approach or both. Another example is the rail road track problem, where we have a rail road tract something like two miles long and it is straight and flat. We are told to jack it up with a jack underneath right in the center, so as to lift the very center up by 1 inch. The question is, how much do the ends move in toward the center? It is a very small amount and it may not be possible to calculate it on some hand calculators because of the limited precision, but going to a higher precision will allow it.
There are other issues that come up too, such as should we consider the curvature of the earths surface that een a flat track has a slight curve to begin with. And we have to be able to convert from miles to inches, etc. We always need some geometry of course.
Then there are the finer points, like what is the temperature of the steel rails, that affects their elasticity, so we dont necessarily end up with a straight track on both sides of the jack. We could specify that it is always straight though to make the problem easier.

So you see there are problems with most questions because there is always an underlying philosophy behind them. We always start with a set of assumptions and end with those same assumptions, unless we find that the solution was just too unreasonable to be accurate.
LEDs vs Bulbs, LEDs are winning.

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Re: What keeps me up late!

Post by Lenp » Sat Jul 29, 2017 2:24 am

i Len,
I am not sure what you are trying to say about the lightening....
Metaphorically speaking, have you never KNOWN that the guy climbing the broken ladder with three cans of paint, hands full of brushes and hanging loose shoe laces was going to have a disaster?

Code: Select all

As to the 'lick' factor....
I'll just start using helium filled plastic pouches, instead of envelopes!
The hot needle in the ocean issue was solved by specific heat capacity
.
Salt or fresh water, wave aeration and height, air speed, humidity, air thermal effect, water mass thermal conduction to land, date and time of year, sun angle, air temperature, heating gain/loss due to the speed and thrust of the sewing needle entering the water, the water's density, PH and salinity, pollution factor, dissolved solids, boat traffic, swimmers, fish population, and many more...
Whoa! You gonna need a ton of instrumentation channels to measure this one!
Each of these kinds of questions are often meant....
By the time you walked from one end of the two mile rail to the other end, the coefficient of expansion probably would have changed the rail or measuring tape length.


About railroad tracks....
The boss told the track crew....Always keep this rail on the right!

West.........................................................East
....---|---|---|---|---
--> ---|---|---|---|---|---|---|---|---|---|---|-- <--
......................---|---|---|---|---|---|---|--
We always start with a set of assumptions and end with those same assumptions
Absolutely correct!
The original post was made in levity, ..... and it still is :grin:
These were not offered as a 'Quod Erat Demonstrandum' moment in life!
Len

“To invent, you need a good imagination and a big pile of junk.” (T. Edison)
"I must be on the way to success since I already have the junk". (Me)

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Re: What keeps me up late!

Post by MrAl » Sun Jul 30, 2017 5:28 am

Lenp wrote:i Len,
I am not sure what you are trying to say about the lightening....
Metaphorically speaking, have you never KNOWN that the guy climbing the broken ladder with three cans of paint, hands full of brushes and hanging loose shoe laces was going to have a disaster?

Code: Select all

As to the 'lick' factor....
I'll just start using helium filled plastic pouches, instead of envelopes!
The hot needle in the ocean issue was solved by specific heat capacity
.
Salt or fresh water, wave aeration and height, air speed, humidity, air thermal effect, water mass thermal conduction to land, date and time of year, sun angle, air temperature, heating gain/loss due to the speed and thrust of the sewing needle entering the water, the water's density, PH and salinity, pollution factor, dissolved solids, boat traffic, swimmers, fish population, and many more...
Whoa! You gonna need a ton of instrumentation channels to measure this one!
Each of these kinds of questions are often meant....
By the time you walked from one end of the two mile rail to the other end, the coefficient of expansion probably would have changed the rail or measuring tape length.


About railroad tracks....
The boss told the track crew....Always keep this rail on the right!

West.........................................................East
....---|---|---|---|---
--> ---|---|---|---|---|---|---|---|---|---|---|-- <--
......................---|---|---|---|---|---|---|--
We always start with a set of assumptions and end with those same assumptions
Absolutely correct!
The original post was made in levity, ..... and it still is :grin:
These were not offered as a 'Quod Erat Demonstrandum' moment in life!

Hi,

Oh ok, gotcha :-)

IN that case, if we put our ear up to the water we can sense anything that might happen to be swimming in the water, hey the American Indians can do it on ground we can do it on water too right :-)
That way we can first see if any sharks are coming our way.

A 'little' more serious...
I like your thoughts on the hot needle problem. This entails a lot of variables. But one thing i will say though is that in a study of such a thing we can have a lot of variables. What we can do is assume we know what level they are at at the time of the calculation, then vary them to fit almost any situation we can think of. That would tell us a lot about how this works. For example, we could first limit the experiment to a small cup of pure water at room temperature, then go from there. We may need higher precision though than we get with the average computer program.

Maybe more importantly this kind of problem shows what might be involved in a real life situation. What is amazing though is what has already been calculated, that almost does not seem possible. The LHC is probably the best example on earth of what can be done when we really want too, yet a black hole shows us what we still cant do.

So we end up with a little pure philosophy again, such as "is a hole in the ground really something physical". It's interesting that the hole is recognized by humans as a physical entity, yet if you put your hand in there, there's nothing there.

We could still have a little fun with this though by quoting some other stuff like this.
Paradoxes are also fun to play around with :-)
LEDs vs Bulbs, LEDs are winning.

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Lenp
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Re: What keeps me up late!

Post by Lenp » Fri Aug 18, 2017 6:29 pm

Here we go again.....with some 'lite' humor.

If you put a light bulb in a light tite box does the light level increase because the light is being stored inside? If this is so than the light switch on a refrigerator door must be a safety device to prevent that blinding flash when the door is opened.
If it is not true, then where does the light go?...:razz:

Since light travels at, round figures, 186,000 miles per second, if you had a high grade fiber optic cable 558,000 miles long, the light would take 3 seconds to travel down the cable. If you put a burst of light into the cable, and within 3 seconds, hook the two ends of the fiber optic cable together, what happens to the light trapped in the cable? :idea:
Phase II....Try it with an electrical pulse.!

Ugg..Another sleepless night :mad:
Len

“To invent, you need a good imagination and a big pile of junk.” (T. Edison)
"I must be on the way to success since I already have the junk". (Me)

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Re: What keeps me up late!

Post by MrAl » Sat Aug 19, 2017 11:07 am

Hi again Len,

I like these questions they are kind of fun to think about. You seem to be good at generating them.

The question of where the light goes is really easy to answer if we take it seriously.
Whenever light strikes an object the wave function breaks down and something changes it. This happens with a dark colored objct, light colored object, or even a mirror. Both the dark and light colored objects absorb energy so the light energy turns into small currents which heat the object. The energy is thus turned into heat, and some reflected to hit another object in the future.
In this way all the light is turned into heat. The heat conducts through the walls of the container, and dissipates out into the surrounding air. If there is little conduction then the heat builds up which causes the temperature to rise. It will rise indefinitely until something melts and breaks down like the emitter.

A mirror is different because more of the light is reflected, but even in a mirror box the light would be partly absorbed and turned into heat, and the place where it is emitted would most likely end up absorbing more.
The interesting part is that if 20 percent is absorbed per wall strike, then 80 percent is reflected but next time it hits a wall another 20 percent is lost, and so on and so forth. So technically the light does get brighter if the reflected part reaches the same surface as the directly incident part, but it still gets absorbed.

The fiber optic cable is about the same deal, where the light gets absorbed eventually. Also, we might be able to form a loop and still have light entering the loop while the other circles back and possibly reinforces the first part. Unfortunately the fiber optic cables of today are lossy and not quite that good. They have an attenuation factor associated with them so that what comes out is always less than what went in.

It's kind of interesting to try to come up with answers to some of these questions too.

I have a flashlight that has 7 high power LED's and when i turn it on and shine it at my hand i can actually feel the heat from the light converting into heat on my hand. It's not the heat of the LED itself heating up, it's the heat that comes from the actual light waves hitting my hand and converting into heat energy. I think the light turns into an electrical current which then turns into heat as it conducts through the surface of the object.

If you study transmission lines in detail, you will find that a lossless transmission line can actually do what you are suggesting with light only with an electrical signal. Space itself can be considered a kind of transmission line that transmits light energy and other waves, and can be lossy or lossless.
A lossless transmission line is made up of pure inductance and pure capacitance with no resistance, but even a single L and C can oscillate forever in theory. We can never take any energy out of it though unless it is for a limited time or else it will stop oscillating. That's the same principle we are talking about here when we talk about light traveling and hitting objects.
LEDs vs Bulbs, LEDs are winning.

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Lenp
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Re: What keeps me up late!

Post by Lenp » Sun Aug 20, 2017 9:32 am

A mirror is different because more of the light is reflected, but even in a mirror box the light would be partly absorbed and turned into heat, and the place where it is emitted would most likely end up absorbing more.
And so...if it is absorbed by the emitter I guess it could also be 're-emited', then would that become an '''optical oscillator" :idea:

LED Heat...
Did you try measuring the LED temperature, with a conventional thermometer? An IR thermometer might get buggy with the LED light.
High output LED's must be heat sinked or they morph into flash bulbs!

Wikipedia says"
"High power light-emitting diodes (LEDs) can use 350 milliwatts or more in a single LED. Most of the electricity in an LED becomes heat rather than light (about 70% heat and 30% light).[1] If this heat is not removed, the LEDs run at high temperatures, which not only lowers their efficiency, but also makes the LED less reliable. Thus, thermal management of high power LEDs is a crucial area of research and development. It is necessary to limit the junction temperature to a value that will guarantee the desired LED lifetime.[2]"
Len

“To invent, you need a good imagination and a big pile of junk.” (T. Edison)
"I must be on the way to success since I already have the junk". (Me)

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