The h Bar

Captain Bohemian

4:24 AM

I am so hungry.

Specter Prophet

5:02 AM

A cup of warm water is suspended in a large pot of water held at a steady boil.
Will the water in the cup ever boil?

Answer is no

When the cup of water is placed in the boiling water, the cup is cooler than the surrounding water and heat will flow into it. Eventually, the water in the cup will increase to 100 degree C if any more energy goes into the cup, then the cup will begin boiling.

But at this point, the boiling water in the pot and the 100 degree C water in the cup are at the same temperature. Since there is no temperature difference, there will be no more heat flow into the cup, so it will never boil.

I got this question from fb from a friend

I think answer is yes

is that explanation saying it takes more than 100 degree c to boil?

assuming atmospheric pressure is same as on earth

sorry i understand it now lol

sorry for asking dumb question

John Rennie

5:25 AM

@SpecterProphet it depends what you mean by "boil". The water in the cup won't form bubbles of steam because forming a bubble requires a temperature greater than 100°C.

Specter Prophet

in other words after boiling point it takes more energy for it to boil since water in pot has heat source it is boiling but water in glass doesn't bave one and it reaches only 100 degree since we know that the heat flow between two bodies will stop once they are at the same temperature

vaugely saying

I have some mistake in statement -_-

John Rennie

When you put a pan on the stove the burner heats the metal to more than 100°C, and this creates the bubbles that you see when water boils in a pan.

But the water itself is at 100°C so it can only heat the cup to 100°C and no higher.

That's why we don't get bubbling inside the cup.

Specter Prophet

looks like there are two types of boiling

and u mean nucleate boiling

John Rennie

@SpecterProphet yes, I mean bubble nucleation.

Specter Prophet

5:40 AM

I think both definition applies

The water outside the cup receives more heat from the heater and starts boiling but as the cup and its surroundings are in equilibrium there is no heat being transferred into the cup this means that the water in the cup is at 100 degrees but it doesn't get more energy to turn into steam and hence it does not boil

I was thinking about phase change than bubble

John Rennie

This is why I said it depends on what you mean by "boil". The water in the cup reaches 100°C and turns into steam. So in that sense it does boil.

But for many people, especially non-scientists, "boiling" means "bubbling".

Specter Prophet

so a scientist will say yes and non scientist will say no?

John Rennie

Probably ...

Protein

The surrounding water is boiling doesn't that mean steam bubbles present can't they be at a temp greater than 100°

Specter Prophet

and it just takes 100 degree c for it to boil not additional energy required to change it's phase if boiling means chf?

John Rennie

5:55 AM

@Protein there is a lot of water and very few bubbles, and the water keeps the temperature at 100°C. The steam inside a bubble will be greater than 100°C, but his won't make any significant contribution to heating the cup.

@SpecterProphet The water to steam change at the surface of the water occurs at 100°C and doesn't need any excess temperature. So the water in the cup will all turn to steam despite its temperature never exceeding 100°C.

Protein

It would be boiling without bubbling?

John Rennie

Yes

Specter Prophet

Heat is needed to increase temperature and change the phase of water in the cup.
Heat transfer can only happen if there is temperature difference.
The reason the water in the pot can boil is because there is temperature difference between the water and the heat source. Since there is also temperature difference between the water in pot and cup, heat transfer into cup happens to increase the temperature of the water in cup to its saturation temperature. However since the water in the pot is always boiling, its temperature is constant so when the water in the cup reached the saturation temper…

But I am wrong since 100 degree Celsius is when water change to vapor so answer it yes it is boiling.

Protein

Vapour pressure of water equals atmospheric pressure . So water is boiling at surface but what about bulk of water is boiling!

Specter Prophet

lol didn't thought it will become this confusing

Boiling is the rapid vaporization of a liquid, which occurs when a liquid is heated to its boiling point, the temperature at which the vapour pressure of the liquid is equal to the pressure exerted on the liquid by the surrounding atmosphere

OK i take Wikipedia definition and accept it boils

ronak jain

6:21 AM

Hi everyone !

Is it possible to have notification like we get from any other apps like whatsapp on stack chat whenever someone ping me ?

Specter Prophet

7:52 AM

@JohnRennie well it seems I am right latent heat makes it have phase change

getting 100 is okay but u need to try to exceed in order to have latent heat and phase change occurs

100 degree c is limit i think

I think i am sloppy but u might get it

Specter Prophet

8:12 AM

ok I was wrong

really depends on boiling def

Captain Bohemian

10:13 AM

It's like in Planck scale, space-time has radically different structure from what it is at macroscopic scale.

Specter Prophet

suppose I submerge a cube in water

will the pressure in bottom side of cube be greater than top?

I think yes

yes it is lol

today I am having dumb question day sorry for interrupting

JingleBells

10:48 AM

What if I have some data, let's say I'm trying to answer if education and IQ affect earnings, and I want to analyze this data and put in a linear regression model to predict earnings based on IQ and education. My confusion is, what if the data is not linear or polynomial? What if it's a mess but there are still patterns that the linear plane algorithm can't capture?

How do I even figure out if plotting all of the independent variables will form a line or a polynomial curve? I mean, with one dependent and one independent variable it's easy because you can plot it and see, but in a situation with multiple independent variables... how do I figure out if the relationship is linear or something like this? How do I figure out if I should use regression models?

Captain Bohemian

How nice if the shop put computers for everyone to use freely.

Slereah

0

Q: What could be introduced to provide a source of propulsion through time?

This Ape has been suspended in a 4 dimensional anti-higgs field time sphere, where as the only source of gravity interfering with this chimp is the interior materials and the chimp itself. What could be introduced to provide a source of propulsion?