Fun Science Factoid Of The Day

[Bravus]

Yeah, the equations for the pendulum require it to have a string of zero mass and a bob that is a point mass, so the denser the better. Lead is a good start, but in a war zone maybe you could pick up some depleted uranium.

[Bravus]

The Skylab astronauts grew 1.5 - 2.25 inches (3.8 - 5.7 centimeters) due to spinal lengthening and straightening as a result of zero gravity.

[Gail]

This is all very interesting but way beyond me!!

I wish I hadn't skipped out of school so much!

[Amelia]

Quote:

The Skylab astronauts grew 1.5 - 2.25 inches (3.8 - 5.7 centimeters) due to spinal lengthening and straightening as a result of zero gravity.

I'm going to assume that they don't feel this elongating in space but what about when they are back on earth. Do they feel themselves shortening? How long does it take to shorten up?

[Bravus]

And we can't ignore the 'human sciences':

In the developing world, fertility rates vary in inverse proportion with literacy rates. For example, Afghanistan, with a female literacy rate of only eight percent has a fertility rate of 6.9 per 1,000 population. Thailand, in contrast, has a literacy rate of 88% and a fertility rate of 2.6/1,000.

[Bravus]

There are roughly 100 times as many water molecules in a glass of water as there are stars in the known universe

[Amelia]

How do you know this? Have you counted all the stars?

[David Koot]

How do you know this? Have you counted all the stars?

Nevah, nevah, nevah understimate Bravus, Amelia!!!

[bevin]

The key phrase was "known universe"

[David Koot]

Indeed. And, that calculation has been made. The boundaries of our universe have been theorized. The most distant observed celestial objects, to date, appear to be near the theoretical limits of this universe.

[Bravus]

I didn't count them all, but these guys did: http://edition.cnn.com/2003/TECH/space/07/22/stars.survey/

Mind you, even they say it's possible there are an infinite number.

[Bravus]

And while we're on astronomy, here's an exciting find just publicised:

http://www.theage.com.au/articles/2007/04/25/1177459786135.html

It's not an alternative home for humans, because the planet is 5 times as massive as earth, so we'd weigh 5 times as much, and we're not built for that, but it looks as though it has liquid water (or at least the potential for same). Wouldn't it be cool if there were living things there?

[D. Allan]

An infinite number? They must be exaggerating a little bit. :)

[Bravus]

Well, I think they are acknowledging that, although most of our best current models see the universe as closed and expanding and of finite though huge extension, there are other models that see it as of infinite extent. In an infinitely large universe you would presumably have an infinite number of stars.

Mind you, 70 sextillion is not infinity, but you can almost see it from there.

But my point was that we can get lost in how huge the universe is, and not realise that the glass of water in our hand contains 100 times as many particles as the number of stars! The simple stuff is amazing too! It's all amazing!

[Bravus]

Here's my rough calculation:

70 sextillion stars is 7 x 10²².

One mole of water contains 6.02 x 10²³ water molecules, weighs 18 grams and fills 18 mls, because water has a density of 1 gram/ml. A cup of water is about 200 ml, or about 11 moles. 11 x 6.02 x 10²³ = 6.7 x 10²⁴... which is roughly 100 times 7 x10²².

[Bravus]

Certain Chinese and American alligators can survive the winter by freezing their heads in ice, leaving their nose out to breath for months on end.

[D. Allan]

I've really goofed. I asked Bevin to host a thread on Astronomy and then here I asked Bravus a question about the stars! Sorry Bevin. And if that was not a big enough goof I also forgot to inform Bravus about the new thread, Stars are God's Fireworks! I'm sorry, Bravus.

I apologize ... to Bevin, Bravus and everybody.

[Gail]

I've really goofed. I asked Bevin to host a thread on Astronomy and then here I asked Bravus a question about the stars! Sorry Bevin. And if that was not a big enough goof I also forgot to inform Bravus about the new thread, Stars are God's Fireworks! I'm sorry, Bravus.

I apologize ... to Bevin, Bravus and everybody.

It's just all part of the fun :)

[Bravus]

Yeah, no worries at all... and we seem to both be happy commenting on each other's threads anyway. I suspect us geeks are just happy to have someone to talk to about the awesomeness of creation.

[D. Allan]

Thanks, guys! BTW wasn't that an awesome movie clip from Nasa that Bevin linked to for us? I just put it on repeat and watched and watched!

[bevin]

No apology needed about the cross-fertilization!

Why don't these alligators and crocodiles get frost-bite?

/Bevin

[Bravus]

Dunno - coldbloodedness?

[Bravus]

The space shuttle has three rocket engines in the back, but there's absolutely no room inside for all the fuel it needs to launch itself up into space. All of that fuel is stored outside the shuttle, in the big brown cylinder, called the external tank.

The tank containing all the rocket fuel weighs seven times more than the space shuttle itself! That's a lot of really heavy fuel, and the space shuttle engines aren't quite strong enough to push the combined weight of the shuttle and the big bloated external tank up off the ground.

That's what the two long white solid rocket boosters strapped onto the sides of the external tank are for. They lift the tank! Fortunately, it was not necessary to strap an infinite series of smaller and smaller rockets to the sides of the solid rocket boosters.

From: http://www.coolsciencefacts.com/

[bevin]

Cool related factoid

The solid fuel motors have a hole right up the middle, and they burn the entire length of this hole, not just at the bottom end.

The fuel itself provides the protection for the surrounding casing during most of the burn...

By changing the shape of the hole, you can change the thrust-over-time curve of the burning rocket. A cylinder has the least surface area initially and, as it burns wider, the thrust grows.

A star-shaped hole is often used - you can get almost constant thrust out of that...

http://en.wikipedia.org/wiki/Space_Shuttle_Solid_Rocket_Booster

Quote:

The propellant is an 11-point star-shaped perforation in the forward motor segment and a double-truncated-cone perforation in each of the aft segments and aft closure. This configuration provides high thrust at ignition and then reduces the thrust by approximately a third 50 seconds after lift-off to avoid overstressing the vehicle during maximum dynamic pressure.

/Bevin

[Bravus]

That is cool - it seems in some ways a low-tech solution to a high-tech problem, in a good way.