| Science Forum Index » Physics Forum » when is jug element hottest-- pour boiling water on... |
|
Page 1 of 2 Goto page 1, 2 Next |
|
| Author |
Message |
| ... |
 Posted: Sat Oct 31, 2009 5:58 pm |
|
|
|
Guest
|
I think this has been answered in the following way. Close to the
element
bubbles of steam do form and then as they rise they cool and collapse
generating the pressure waves (compression and rarefaction) to cause
the
surface of the water and the surface of the kettle to emit the white
noise.
I noticed that plastic jugs (and probably ceramic ones with an
element) are
quieter.
Don't take my word I am recalling this from some older publication -
possibly Scientific American.
Andrew-----Original Message-----
Sent: Friday, 30 October 2009 10:35 AM
Cc: letters newscientist; ch reptr 474-0196 dompost; nz herald;
newswn;
news at (no spam) radionz.co.nz
Subject: Re: water over teabag. when is surface of jug element
hottest?
discuss.
Great Question, Thanks Vicki,
b cc ; wass, nzmy, frank tom, MZD andrew nzsm ij newsct newss//./
answer follow.. below..., cheers 30/10/2009.
[quote]Subject: Re:
[/quote]
water over teabag. when is surface of jug element hottest? discuss.
[quote]Received: Thursday, 29 October, 2009, 5:38 PM
Actually Don, what I want to know is why
there is such> a great noise
when it is heating? There are no moving parts. Is it merely
the thermal expansion [don no..] of the metal bits? Does the water make
a noise? [yes don.]
The hottest time for water is when it is expanded and just
before all the bubbles come and go. Or is it?
in antarctica boiling water sinks ??[/quote]
I use my senses when make cuppa Yes!
My second electric jug makes a different sound.
It sounds OFF, not on, for 30 seconds.
then starts to warm.
i think it is warming the element through.
The centre is hotter.
The question was temperature of element NOT water please.
heat radiates..., helix torus?
only as the surface ***of ELEMENT reaches 100 Deg C it achieves
Incipient ??
boiling. tiny explosive bubbles.
It takes another 2 mins nearly to really boil
+ boils for 30 sec before auto off.
does toaster make noise -- probably, too !
you cannot see the element*** no lid ON ELECTRIC jug.
it has minimum level marker. but is that the top of element?
or recommend efficient safe safety margin.
i also been thinking.
if element barely / not fully covered
only surface of water boiling
and not large convection agitation to spread heat through.
result pour water onto teabag, not really average 100 deg º C boiling.
talk some more. |
|
|
| Back to top |
|
|
|
| Geopelia... |
| Posted: Sun Nov 01, 2009 8:13 pm |
|
|
|
Guest
|
It would be hard to make tea on top of Mt Everest. The higher you go, the
cooler the water is when it boils.
But would a kettle boil in a spaceship, and at what temperature? |
|
|
| Back to top |
|
|
|
| Sam Wormley... |
| Posted: Sun Nov 01, 2009 8:27 pm |
|
|
|
Guest
|
Geopelia wrote:
[quote]It would be hard to make tea on top of Mt Everest. The higher you go, the
cooler the water is when it boils.
But would a kettle boil in a spaceship, and at what temperature?
[/quote]
See: http://www.hi-tm.com/Documents/Calib-boil.html
What's the pressure in the spaceship? |
|
|
| Back to top |
|
|
|
| Lawrence D'Oliveiro... |
| Posted: Mon Nov 02, 2009 12:59 am |
|
|
|
Guest
|
In message <hclbon$slr$1 at (no spam) news.eternal-september.org>, Geopelia wrote:
[quote]But would a kettle boil in a spaceship, and at what temperature?
[/quote]
I believe NASA pressurizes its spacecraft to a third of a standard
atmosphere. At that pressure, according to the vapour-pressure formula here
<http://en.wikipedia.org/wiki/Vapour_pressure_of_water>, water would boil at
about 346 K, which is about 72°C. |
|
|
| Back to top |
|
|
|
| G=EMC^2 Glazier... |
| Posted: Mon Nov 02, 2009 8:26 am |
|
|
|
Guest
|
Pelia Spaceship has "airpressure" and thus your answer. Water
molecules can not exist in the vacuum of space.for more than one reason
Bert |
|
|
| Back to top |
|
|
|
| G=EMC^2 Glazier... |
| Posted: Mon Nov 02, 2009 8:29 am |
|
|
|
Guest
|
Sam when I lived at lakeTahoe in Nevada in was not easy making hard
boiled eggs not hard to figure Bert |
|
|
| Back to top |
|
|
|
| Sam Wormley... |
| Posted: Mon Nov 02, 2009 12:34 pm |
|
|
|
Guest
|
G=EMC^2 Glazier wrote:
[quote]Sam when I lived at lakeTahoe in Nevada in was not easy making hard
boiled eggs not hard to figure Bert
[/quote]
I didn't have trouble hard boiling eggs at high altitude.
Take a cooking course, Herb! |
|
|
| Back to top |
|
|
|
| G=EMC^2 Glazier... |
| Posted: Mon Nov 02, 2009 2:26 pm |
|
|
|
Guest
|
sam How high up are you? Love to cook. Boiling water at sea level on
Revere Beach and then up 5500 feet makes a time difference. You can do
the math O ya Bert |
|
|
| Back to top |
|
|
|
| Sam Wormley... |
| Posted: Mon Nov 02, 2009 2:42 pm |
|
|
|
Guest
|
G=EMC^2 Glazier wrote:
[quote]sam How high up are you? Love to cook. Boiling water at sea level on
Revere Beach and then up 5500 feet makes a time difference. You can do
the math O ya Bert
[/quote]
Mostly around 7,600 feet, but have boiled water at least once at 10,000 ft.
Take a cooking class, Herb. |
|
|
| Back to top |
|
|
|
| G=EMC^2 Glazier... |
| Posted: Mon Nov 02, 2009 5:27 pm |
|
|
|
Guest
|
Sam Its simple physics and no cooking lessons needed. Want to save
energy at high altitudes use a pressure cooker,orjust scramble the eggs.
Not many people boil eggs any more,They have that cheap breakfast at
Denneys. Bert. |
|
|
| Back to top |
|
|
|
| Sam Wormley... |
| Posted: Mon Nov 02, 2009 11:56 pm |
|
|
|
Guest
|
G=EMC^2 Glazier wrote:
[quote]Sam Its simple physics and no cooking lessons needed. Want to save
energy at high altitudes use a pressure cooker,orjust scramble the eggs.
Not many people boil eggs any more,They have that cheap breakfast at
Denneys. Bert.
[/quote]
That's a shame--I boil eggs as often as all the other ways
to cook them. They make excellent toast sandwiched for breakfast. |
|
|
| Back to top |
|
|
|
| G=EMC^2 Glazier... |
| Posted: Tue Nov 03, 2009 9:35 am |
|
|
|
Guest
|
Sam should I put the eggs in a micro wave oven? I think they will
explode(what a mess) Still worth a try. Might be good for making "sunny
side up." or an omelet. I only cook now adays with micro oven. I think
every space ship should not leave Earth without a micro oven.. I have
one in my conversion van. Fact is thinking boiling water micro wave does
it best for obvious reason Bert |
|
|
| Back to top |
|
|
|
| Sam Wormley... |
| Posted: Tue Nov 03, 2009 1:25 pm |
|
|
|
Guest
|
G=EMC^2 Glazier wrote:
[quote]Sam should I put the eggs in a micro wave oven? I think they will
explode(what a mess) Still worth a try. Might be good for making "sunny
side up." or an omelet. I only cook now adays with micro oven. I think
every space ship should not leave Earth without a micro oven.. I have
one in my conversion van. Fact is thinking boiling water micro wave does
it best for obvious reason Bert
[/quote]
Microwaving things damages and destroy a lot of nutrients and enzymes.
It's really too bad you eat a lot of "deadened" food, Herb! That's sad! |
|
|
| Back to top |
|
|
|
| G=EMC^2 Glazier... |
| Posted: Tue Nov 03, 2009 5:32 pm |
|
|
|
Guest
|
Sam reality is all my frozen foods have been precooked at the factory. I
just heat them up.Do not go out to eat hardly. Have a negative
income,and to sit alone in a fancy restraunt is boring. I eat and watch
the 6pm news. This Thanks Giving I will cook a small pot roast just
like my mother made for me in the good old days O ya bert |
|
|
| Back to top |
|
|
|
| Sam Wormley... |
| Posted: Tue Nov 03, 2009 6:05 pm |
|
|
|
Guest
|
G=EMC^2 Glazier wrote:
[quote]Sam reality is all my frozen foods have been precooked at the factory. I
just heat them up.
[/quote]
No you don't just heat them! You alter molecules too!
Do some research Herb!
Compare steamed Broccoli with microwaved Broccoli, for instance! |
|
|
| Back to top |
|
|
|
|
