this post was submitted on 07 Oct 2023
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127
Thermal Energy Intuition (lemmy.ml)
submitted 11 months ago by [email protected] to c/[email protected]
13 comments fedilink hide all child comments
 
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[–] [email protected] 33 points 11 months ago* (last edited 11 months ago) (3 children)

If you don't get it:

It takes the same amount of energy to increase the temperature of water by ~70°C (room temp=30°C and boiling point = 100°C) as it takes to send that cup of water 30 000 meters into the air. (If I did the math right)

[–] [email protected] 10 points 11 months ago* (last edited 11 months ago) (2 children)

My math: Boiling a cup (0.24 kg) of water from 25°C to 70°C ~45kJ (0.24kg×45°C×4182J/kg°C) Raising 0.24 kg of water up a height 30,000 m ~ 71kJ (0.24kg × 9.8m/s^2 × 30,000 m)

So my math says raising the temp of a cup of water from room temp would be equivalent to raising it about 19 km high.

Edit: I'm a moron who can't read, boiling water from 25 to 100 °C takes:

0.24 kg × 75 °C × 4182 J/kg°C ~ 75kJ

[–] [email protected] 13 points 11 months ago* (last edited 11 months ago) (2 children)

Water boils at 100°C

[–] [email protected] 7 points 11 months ago (1 children)

God I'm stupid. I misread what you wrote as raising water to 70°, not raising water by 70°, without even thinking that that's not how you make tea. Fixed my math, and the numbers now check out.

[–] [email protected] 1 points 11 months ago

Actshually, that is how you make green tea

[–] [email protected] 5 points 11 months ago

They could drink green tea, which seeps at around 70.

Or that could be jasmine, its one of them.

[–] [email protected] 1 points 11 months ago

In the ISA atmosphere model, the tropopause starts at an altitude of 11 km. So you might be able to say that 19 km counts as 'stratosphere'.

[–] [email protected] 3 points 11 months ago (1 children)

Now if only we could figure out a way to actually do that without burning a bunch of fuel for the purpose of lifting fuel! Something something tyranny of rockets.

[–] [email protected] 2 points 11 months ago

As with so many problems, this one can be solved with a suitably large cannon. Why you'd want to fire cups of water into the stratosphere is left as an exercise for the interested reader.

[–] [email protected] 1 points 10 months ago

The general formula:

MCT=MGH

So height=(heat capacity of liquid*change in temp)/9.81

In our case (4184*70)/9.81 ~ 30,000 meters

[–] [email protected] 12 points 11 months ago

We could be running several space habitats by now if people just weren't drinking so much tea.

[–] [email protected] 7 points 11 months ago* (last edited 11 months ago)

Bertrand Russell looking at his teapot

[–] [email protected] 4 points 11 months ago

Is there a site that does a variety of energy comparisons