|
edit: Updated with my response, thanks for the discussion.
Just had this question on a test. I think it's just a poorly thought-out question and the answer is somewhat up to interpretation. What do TL'ers think? Obviously only answer if you think you know what the answer should be and feel free to give an explanation.
"When a thermometer is submerged in a liquid, the Zeroth Law of Thermodynamics tells us that the temperature of the thermometer is the same as that of the liquid"
a) True
b) False
Poll: So...False (48) 80% True (12) 20% 60 total votes Your vote: So... (Vote): True
(Vote): False
I'll hold off a bit on saying what I answered and why.
Fun fact: This is the first google image results for "thermodynamics" as I've just discovered:
+ Show Spoiler +
I said false thinking that the zeroth law wasn't applicable since there weren't 3 distinct objects/systems present and the question never mentions anything about equilibrium or if the thermometer has been submerged for a long period of time.
|
Assuming that the system is in thermal equlibrium yes.
However the question says nothing about that so the correct answer should be "not necessarily"? I dunnu.
|
its not necessarily equal, if you heat up the thermometer then put it into liquid it would take time to reach equilibrium
|
On April 19 2011 06:55 KlaCkoN wrote:
Assuming that the system is in thermal equlibrium yes.
However the question says nothing about that so the correct answer should be "not necessarily"? I dunnu.
Didn't take very long for someone to nail it.
|
I'd say yes. q= m *C *deltaT right? Also, that comic is pretty funny haha
|
Its a shame I know nothing of this subject, I hate looking at pictures and not understanding what it means. I feel like I am missing out on a joke... perhaps someone can explain the comic to me?
|
On April 19 2011 07:14 WarChimp wrote:
Its a shame I know nothing of this subject, I hate looking at pictures and not understanding what it means. I feel like I am missing out on a joke... perhaps someone can explain the comic to me?
Thermodynamics state that the universe is heading into increased (entropy) chaos.
|
United States5162 Posts
I've never heard of the Zeroth Law, so after Googling it I found it's a generalization about things in equilibrium. As such, I think if something is following the Zeroth Law that you would assume it's in equilibrium or else the Zeroth law wouldn't apply at all.
EDIT; However, in this case I think the answer would be false because the Zeroth law deals with 3 objects, not two.
|
Calgary25951 Posts
I don't get why everyone voted yes. In my eyes, this situation isn't even related to the zeroth law of thermodynamics.
So no.
|
Calgary25951 Posts
On April 19 2011 07:18 Myles wrote:
I've never heard of the Zeroth Law, so after Googling it I found it's a generalization about things in equilibrium. As such, I think if something is following the Zeroth Law that you would assume it's in equilibrium or else the Zeroth law wouldn't apply at all.
It also talks about three bodies. As such, should we just assume there's some other relevent third body too? O_o
|
On April 19 2011 07:19 Chill wrote:Show nested quote +On April 19 2011 07:18 Myles wrote:
I've never heard of the Zeroth Law, so after Googling it I found it's a generalization about things in equilibrium. As such, I think if something is following the Zeroth Law that you would assume it's in equilibrium or else the Zeroth law wouldn't apply at all. It also talks about three bodies. As such, should we just assume there's some other relevent third body too? O_o
Yeah. Was reading it on wikipedia, and where the hell is the third body o.o
|
United States5162 Posts
On April 19 2011 07:19 Chill wrote:Show nested quote +On April 19 2011 07:18 Myles wrote:
I've never heard of the Zeroth Law, so after Googling it I found it's a generalization about things in equilibrium. As such, I think if something is following the Zeroth Law that you would assume it's in equilibrium or else the Zeroth law wouldn't apply at all. It also talks about three bodies. As such, should we just assume there's some other relevent third body too? O_o
Yup(well, no to your question...but you get it), after stepping back for a second it became clear this is just a cleverly disguised question on whether you know what the Zeroth law is, not whether anything is actually in equilibrium.
|
On April 19 2011 07:21 Froadac wrote:Show nested quote +On April 19 2011 07:19 Chill wrote:On April 19 2011 07:18 Myles wrote:
I've never heard of the Zeroth Law, so after Googling it I found it's a generalization about things in equilibrium. As such, I think if something is following the Zeroth Law that you would assume it's in equilibrium or else the Zeroth law wouldn't apply at all. It also talks about three bodies. As such, should we just assume there's some other relevent third body too? O_o Yeah. Was reading it on wikipedia, and where the hell is the third body o.o
If there's no 3rd body, then doesn't that mean the Zeroth Law isn't telling us anything in this situation so the answer is just false?
|
That is an example of a question that is a terrible true or false question. Both answers are wrong as the temperature could be the same or different.
|
United States5162 Posts
On April 19 2011 07:34 SirazTV wrote:
That is an example of a question that is a terrible true or false question. Both answers are wrong as the temperature could be the same or different.
It's actually not. The question isn't about the temperature or equilibrium at all. It's about what the Zeroth Law tells us, which in this case is nothing because the Zeroth law applies to 3 bodies, not 2.
|
Calgary25951 Posts
On April 19 2011 07:34 SirazTV wrote:
That is an example of a question that is a terrible true or false question. Both answers are wrong as the temperature could be the same or different.
But even if it's the same, the zeroth law doesn't tell us that.
|
It's a combination of the first and second laws of thermodynamics that tells you an object placed in contact with a thermal reservoir (allowing heat to pass between them) will result in the thermometer measuring the temperature of the liquid (eventually).
Assuming the thermometer is intended to be the object and the liquid is well approximated as a thermal reservoir, and that the thermometer actually works (sort of by definition it must, or it's not a thermometer), anyway.
You do need the zeroth law I think, to define what is meant by thermal equilibrium though. So in that sense it's true.
Also I've written the word thermometer so many times it no longer looks like a real word any more.
|
On April 19 2011 07:25 dudeman001 wrote:Show nested quote +On April 19 2011 07:21 Froadac wrote:On April 19 2011 07:19 Chill wrote:On April 19 2011 07:18 Myles wrote:
I've never heard of the Zeroth Law, so after Googling it I found it's a generalization about things in equilibrium. As such, I think if something is following the Zeroth Law that you would assume it's in equilibrium or else the Zeroth law wouldn't apply at all. It also talks about three bodies. As such, should we just assume there's some other relevent third body too? O_o Yeah. Was reading it on wikipedia, and where the hell is the third body o.o If there's no 3rd body, then doesn't that mean the Zeroth Law isn't telling us anything in this situation so the answer is just false?
Ugg yeah, re-reading the question and remembering what the zeroth law actually says I think that's right.
Stupid question imo :p
|
Just a badly written question is all. Happens all the time on tests unfortunately. If really pushed I'd go with "no" because the zeroth law doesn't seem to have much to do with this situation, but I wouldn't feel good about it.
|
On April 19 2011 07:36 Myles wrote:Show nested quote +On April 19 2011 07:34 SirazTV wrote:
That is an example of a question that is a terrible true or false question. Both answers are wrong as the temperature could be the same or different. It's actually not. The question isn't about the temperature or equilibrium at all. It's about what the Zeroth Law tells us, which in this case is nothing because the Zeroth law applies to 3 bodies, not 2.
Lol, you are completely missing the point of the Zeroth Law of thermodynamics.........
The point is that the liquid, glass, mercury, and air are all in equilibrium with each other. Without the zeroth law even if the liquid and glass were in equilibrium and the glass and mercury were in equilibrium. The liquid and mercury would not be in equilibrium. Without this it would be impossible to measure temperature.
Look, just because in grade school math A=B, B=C ==> A=C does not mean it is always the case.
|
|
|
|
|
|
EPT![[image loading]](http://i54.tinypic.com/2gv1ona.gif)
