Centripetal Force

Why is it when you spin something, it stays on the plane that you spin it on? Does gravity not affect it? I would think that it would... in b4 gb2/4th grade science/

Inertia--mainly rotational inertia. Gravity is not strong enough on this planet to suck the water out of the pale when you're spinning it fast enough.

She could suck the water out of a pail

gb2usingcommonsense

but like if your spinning it parallel to the ground, ie a lasso. after a while it spins in a circle, and doesn't seem to be pulled by gravity?

unrelated, but its been bugging the _shit_ out of me:

http://imgs.xkcd.com/comics/substitute.png

number 1 can be solved with a bit of work, but how would you go about solving number 2?

DW, in 100000 years they'll come up with a theory for quantm gravity.

A bucket of water on a rope and a spinning top or gyroscope work on different principles.
Bucket of water stays up/full because of inertial effects (centripetal 'force' isn't really a force, it's just easier to pretend it exists for mathematical purposes).
Spinning top stays upright thanks to gyroscoping precession - any force attempting to shift the orientation of the axis of rotation will produce another force that is perpendicular to both the axis of rotation and the external force.

Probably worth noting that angular momentum is the thing driving the 'gravity-defying' effects you can get using a gyroscope.

>>6
I tried plotting the position of the raptors. It needs the vector from it's position to my position and then accelerate towards me with max. velocity. I couldn't figure out how to get the vector.

>>8
>>9
thank you for that nugget of knowledge. anonymous delivers.

and anyway, i found out that xkcd has a forum discussing that problem. so far, the math solution comes out to be


angle between raptors * ( speed of wounded raptor / (speed of wounded raptor + speed of non-wounded raptor) )
120 * ( 10 / (10 + 25) )
~= 34.285 degrees
or 274.285 degrees
http://forums.xkcd.com/viewtopic.php?t=120

someone also made a program to simulate the situation, and it comes out a bit different, but needless to say you'll still get eaten in 3 seconds. still, its interesting...

also, does anyone find it remotely interesting that all the planets orbit in the same direction? sorry.

>>12

As you probably know, back before the sun was a star it was just a big cloud of dust left over from when another star exploded.  The dusk cloud was spinning as one large mass, and so all the particles were moving in the same direction.  Over time, as these particles accreted into planets they kept their same counter-clockwise(?) direction.

It's still pretty cool though.

>>13

http://www.nrao.edu/pr/2006/counterdisk/
^ If I got a star system like this, I'd ask for a refund.
BTW Counter-clockwise assumes Eart-North = up.
Damn northerners.

>>14
you got that when you googled it too huh? so did i lol.

and i just thought it was interesting because while wikipedia-ing angular velocity, the force goes down when spinning one way, and up when spinning the opposite. but yea i forgot that everything was once a big spinning cloud of stuff. are there any comets or asteroids that spin in the opposite direction of the planets?

i was just thinking, why hasn't our solar system caught anything going in the opposite direction yet. like, just a random passerby that goes into orbit in the opposite direction. given though, that it probably wouldn't last long with all the other planets and stuff coming straight for it.

Asteroids are s'posed to be remnants from the original formation - they just got messed up because they were too close to Jupiter, so there was too much gravitational interference. I'm pretty certain there's some bits of interstellar junk flying around the wrong way; if I remember right a fair number of comets aren't anywhere near the same plane as the planets either. They sorta fly in at an angle and get hurled back out again.