My roomate said that this happens all the time.. ?
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My roomate said that this happens all the time.. ?
Also the interaction of the Earth and the Moon have an effect. When there is a shift in the Earth it causes a shift in the moon which affects the torque of rotation.
The Moon pulls the water and to a slight deggree the crust. There is a bulge on the side of the Earth the moon is on and the opposite side. These are the tides. But because the Earth is spinning the bulge is slightly ahead or behind of the moon, I forget which. And this causes a torque that is slowly slowing down the rotation of the Earth and increasing the rotation of the moon. Days are slightly longer than they used to be. In dinosaur times I believe that the day was only 23 hours long!
I imagine that any major Earthquake could have an effect because of this principle as well. The opposite reaction could be compensated by the Moon instead of by the Earth. So it would be like running down the street with your little brother and instead of pushing against yourself to slow down you push against your little brother. He speeds up and you slow down.
Well yeah, with all strong earthquakes I guess. If you pay attention after some strong, newsworthy earthquake you'll see that they always, or usually at least, tell us how the day is shorter etc.Quote:
Originally Posted by dajo
http://www.nasa.gov/topics/earth/features/earth-20100301.html
I thought it was because it shifted the mass of the Earth closer to the center, like an ice skater spinning faster when they pull their legs in...
Where i live, my city was on Tsunami watch. Nothing hit us, but if it did it would have been the tail end of the Tsunami.
Yep, exactly that. It's called the conservation of angular momentum.Quote:
Originally Posted by The Invisible Man
What are you, google?Quote:
Originally Posted by Xei
Bizarrely I'm currently studying a dynamics course and about an hour ago I learnt the mathematical proof for the conservation of angular momentum. So it's quite solidly in my brain. :V
It's quite famous though. I've got a cool geomag model which demonstrates it, you spin the thing and the pull both ends so it elongates and it spins much faster. Ice skaters are the canonical example.
Seriously how great will you feel should you ever go ice skating now and be able to recite the physical principles involved...
YES I AM A NERD.
The mass of the Earth would have to be moved away from the center in this case, not closer to.
EDIT: Nevermind.
I wish I had something meaningful to contribute now.....
This is kinda awkward.
Chilean City Moved 10 Feet West in Quake - Geologists think quake will be most important ever studied
So does the angular momentum apply in this case? I'm really curious.Quote:
Originally Posted by Invader
Quote:
Originally Posted by dajo
I have to admit, that is pretty impressive! :shock:
Damn George W. Bush for the earthquake in Chile! It's about oil.
That depends on where the center of mass of the earth is. It's possible for a landmass to move in any of the cardinal directions and still remain the same distance from the center of mass (especially if the CoM is in the direct center of the Earth), in which case the Earth's moment of inertia would not change. Mass that shifts distance from the CoM however will effect the moment of inertia, and cause a proportionally opposite change in angular velocity.Quote:
Originally Posted by dajo
A person doing a backflip for instance will tuck in mid air. Since they are reducing their moment of inertia by bringing mass closer to the center of their body, their angular velocity must increase in order for momentum to remain conserved.