Alright Science/Physics Geeks

#26
#26
I think were are thinking wrong about it being any kind of expansion.
I think The vacuum is using the energy of the heat to create the vacuum.
Or more to the point the heat energy is causing the vacuum.
 
#28
#28
volinbham said:
I was kinda wondering along those lines - if somehow a change in pressure within the vaccuum section actually pushes the inner metal inward.
Click to expand...

:question:

Question: Is the inside of the cup metal, also? I assumed it was. If so, then maybe (maybe), the thermal coefficient of expansion for the inside material is less than the material for the metal exterior of the cup (I'm asuming there are two different metals on the inside vs outside of cup.

If that is the case, the outside will expand at a faster rate than the inside. Add in the drop in pressure of the inside of the cup as the coffee cools, and that may be reason it feels tight, also.

At this point, just throwing crap on the wall because I don't have the cup in front of me to look at it and see how the cup and lid are made.
 
#31
#31
Rasputin_Vol said:
:question:

Question: Is the inside of the cup metal, also? I assumed it was. If so, then maybe (maybe), the thermal coefficient of expansion for the inside material is less than the material for the metal exterior of the cup (I'm asuming there are two different metals on the inside vs outside of cup.

If that is the case, the outside will expand at a faster rate than the inside. Add in the drop in pressure of the inside of the cup as the coffee cools, and that may be reason it feels tight, also.

At this point, just throwing crap on the wall because I don't have the cup in front of me to look at it and see how the cup and lid are made.
Click to expand...

The material seems to be the same inside and out. It's a basic silver vacuum coffee mug. The amount of vacuum space at the top is very small - the inside circumference of the mug is constant but the outside tapers in at the top.

It really doesn't feel like the lid is being sucked down - it just feels like the lid got bigger (or the mug got smaller).
:dunno:
 
#32
#32
Clearly I'm bored - here's a picture of the little bugger.
 

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#36
#36
volinbham said:
I was kinda wondering along those lines - if somehow a change in pressure within the vaccuum section actually pushes the inner metal inward.
Click to expand...

I'm not sure there would be enough gas in the "vacuum" section to cause enough expansion and pressure when heated to force the metal in any direction.

As for the suction idea...If you microwave something with a lid on it and then take it out, the lid will get tighter from the suction as the gases cool inside (I guess as it heats up the gases actually push out of the gaps around the lid, but as it cools it sucks the lid down making it more airtight causing the "collapse" of the container in some cases).

You will definitely create some suction if you put a lid over some hot coffee and then the coffee cools...but this sounds like the coffee is still hot and the lid is tight...which takes me back to metal expansion....I think that you are right about the inner circumference increasing when heating if we are talking about a hole through a metal plate...the plate expands out and the hole gets bigger...but I think that it is different for a tube...I think the ID gets a big smaller and the OD gets a quite a bit bigger...but....now (as I edit) I think that I might be wrong about that. I told you that seeing me try to answer this was going to be entertaining...guess I should have taken a materials class somewhere along the way!

...yet another edit....this isn't your typical "ring" expansion, right....you have the flat metal at the top that then goes down into the two edges of the vacuum space. I'm wondering how that influences the expected characteristics...
 
Last edited:
#38
#38
Rasputin_Vol said:
:question:

Question: Is the inside of the cup metal, also? I assumed it was. If so, then maybe (maybe), the thermal coefficient of expansion for the inside material is less than the material for the metal exterior of the cup (I'm asuming there are two different metals on the inside vs outside of cup.

If that is the case, the outside will expand at a faster rate than the inside. Add in the drop in pressure of the inside of the cup as the coffee cools, and that may be reason it feels tight, also.

At this point, just throwing crap on the wall because I don't have the cup in front of me to look at it and see how the cup and lid are made.
Click to expand...

Yeah...that was why I was asking if this was a design feature....that maybe they designed it with different metals to cause this effect...but it doesn't sound like it is necessarily meant to happen.
 
#39
#39
volinbham said:
I assumed plastic wouldn't expand or would expand less than metal. :dunno:
Click to expand...

Just checked the expansion coefficients for plastics
and stainless steel,seems plastic in general expans
up to 9 times as much as stainless.According to the
coefficients.making the plastics extremely sensitive to temperature and temperature changes.
 
#40
#40
Gosh I hope the undecided recruits are following tihs thread! We'll land the top class for sure.
 
#41
#41
orangeblooded2 said:
Just checked the expansion coefficients for plastics
and stainless steel,seems plastic in general expans
up to 9 times as much as stainless.According to the
coefficients.making the plastics extremely sensitive to temperature and temperature changes.
Click to expand...

Interesting....this is the case for plastics in general or specific plastics? That surprises me...but then again, I don't know much about materials at all...
 
#42
#42
orangeblooded2 said:
Just checked the expansion coefficients for plastics
and stainless steel,seems plastic in general expans
up to 9 times as much as stainless.According to the
coefficients.making the plastics extremely sensitive to temperature and temperature changes.
Click to expand...

I bet the lid is made from gorilla foreskin. What's the expansion coefficient when VBH starts rubbing on that?

I bet he rubs long enough and it converts to a thermos.
Posted via VolNation Mobile
 
#43
#43
orangeblooded2 said:
Just checked the expansion coefficients for plastics
and stainless steel,seems plastic in general expans
up to 9 times as much as stainless.According to the
coefficients.making the plastics extremely sensitive to temperature and temperature changes.
Click to expand...

If the plastic is expanding more than the metal it is the simplest answer. It really does feel as if the lid gets larger. I just never thought of plastic as expanding/contracting more with heat than metal does.
 
#44
#44
BigPapaVol said:
I bet the lid is made from gorilla foreskin. What's the expansion coefficient when VBH starts rubbing on that?

I bet he rubs long enough and it converts to a thermos.
Posted via VolNation Mobile
Click to expand...

While I have been compared to a gorilla and a thermos I don't believe that's what's going on here...:)

---signed Smiling Bob the Enzyte guy.
 
#45
#45
TennTradition said:
Interesting....this is the case for plastics in general or specific plastics? That surprises me...but then again, I don't know much about materials at all...
Click to expand...

It varies for the temperature and the type of plastic.
Were as stainless is fairly constant across the board.
 
#47
#47
volinbham said:
While I have been compared to a gorilla and a thermos I don't believe that's what's going on here...:)

---signed Smiling Bob the Enzyte guy.
Click to expand...

I assume you play pick up ball with buddies who think you're tough and they believe when you're hot, you're hot, when you're not, you're not.
Posted via VolNation Mobile
 
#48
#48
orangeblooded2 said:
Just checked the expansion coefficients for plastics
and stainless steel,seems plastic in general expans
up to 9 times as much as stainless.According to the
coefficients.making the plastics extremely sensitive to temperature and temperature changes.
Click to expand...

Link?
 
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