#surface area

[num8ers]

[whats-in-a-sentence]

Were you to double the radius of a black hole, its volume would increase by a factor of 8 (2³) while its surface area would increase by only a factor of 4 (2²); were you to increase its radius by a factor of a hundred, its volume would increase by a factor of a million (100³), while its surface area would increase only by a factor of 10,000 (100²). Big black holes have much more volume than they do surface area.²

2. You will note that it doesn't really make much sense to compare a volume with an area, as they have different units. What I really mean here, as indicated by the text, is that the rate at which volume grows with radius is much faster than the rate at which surface area grows. Thus, since entropy is proportional to surface area and not volume, it grows more slowly with the size of a region than it would were it proportional to volume.

"The Fabric of the Cosmos" - Brian Greene

[zespaceblog]

and no, please don't ask where Uranus is, as the answer will involve gases and a little methane. 🤣

Source :

Surface Area

[oroes-constellation]

With the Helios Star System, what does it exactly mean by 'Everything to do with astrophysics'?

By that I mean everything I have calculated about the planets and stars of the Helios System, from a physics (this branch being called astrophysics) angle.

All the things I’ve calculated for all are:

Radii/Diameters

Luminosity of the star aka Helios

Hill Sphere (the closest an object can orbit without being pulled in by the larger objects gravitational pull)

Mass

Gravity

Average surface temperature + Core temperature of Helios

Orbit radius (distance from star)

Orbital period (length of year)

Orbital speed (how fast it moves along its orbit)

Bond Albedo (how much light is reflected by the surface)

Average density of the planets

Water % on surface (for most)

Surface Area & Atmospheric Pressure for half

So most of the sciency stuff to do with the Helios system I’ve got covered.

When it comes to more people oriented and culture stuff, the countries that exist there I’ve got pretty much nothing- so that’s what I mean by ‘everything to do with astrophysics.’

[materialsscienceandengineering]

Laser-pelted, citric acid-washed copper could boost heat transfer

The principle of pool boiling—heating a surface submerged in standing liquid until that liquid boils—is used to transfer heat for many applications, from power generation to refrigeration to air conditioning.

Increasing the rate and efficiency of that heat transfer can improve the performance and reliability of systems that rely on pool boiling. One popular method? Engineering the surfaces of thermally conductive materials to increase their surface area, even down to the microscale or nanoscale.

To that end, Nebraska's Jeff Shield, George Gogos, Craig Zuhlke and their graduate students are investigating the effects of pelting material surfaces with laser pulses that last just picoseconds. (One picosecond compares to a second as a second compares to 31,710 years.)

Read more.

[indizombie]

Sebastian Pfautsch, an urban heat expert at Western Sydney University, proposes replacing the model of runaway suburban sprawl with one that prioritises green space. He's calculated that in some Western Sydney's suburbs, 80 per cent of the surface area is sealed with roads, pavements, car parks buildings and other kinds of construction that trap heat. That figure, he says, needs to get down to 25 per cent. "If you don't want to have urban development where you increase the temperature then you can only achieve that where you're the covering area with two portions open space and one portion of closed space," he says. To do this, he says, houses and shops need to be built largely underground, which has the added advantage of making them easier to cool. Another option is to house people in high apartment blocks surrounded by vast areas of parkland. "We need to build up or build down," he says. "This may sound utopian but it is a necessary type of progressive thinking in hot areas. "A large shopping centre built underground can bring its cooling cost down by 95 per cent..." Dr Pfautsch points out that poorly insulated houses with heat-absorbing black roofs are still being constructed in great numbers out west. Unsuspecting buyers chasing the Australian Dream are being locked into decades of sweltering heat. "When it comes to development itself, I cannot say that I see any change," Dr Pfautsch says. "How long can we afford to build these hotboxes that will at least be there for 30 to 60 years?"

James Purtill, 'Heatwaves may mean Sydney is too hot for people to live in 'within decades'', ABC

[literaturebylamplight]

Today is the day, my friends! I am awake. I am alive. I am full of decaf coffee. The world is mine and I can see God. Anyway, here are some sexy as hell calculus notes, courtesy of ya girl, complete with hand drawn graphs and diagrams.

I've spent the last three weeks listening to nothing but the "oldies playing in another room and its raining"playlist on YouTube and It’s the only thing keeping me going through this pandemic and election season.

Also, my current hyperfixation is piracy (???) so if anyone has some good book recommendations I'd love to hear them!

[factoidfactory]

Random Fact #3,252

Earth’s surface area is 510,064,472 km2