Earth spinning?

[salim271]

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So the Earth spins around an axis... so it has torque. What caused the earth to start spinning in the first place? I kind of understand why its still spinning based on my epic knowledge of google search (because there's no force large enough acting in such a way that stops its spinning), but what caused it to spin in the first place?

Also, since the movement of Earth around the sun is slightly elliptical, does that mean it follows simple harmonic motion? Why is it slightly elliptical?

 

[gunj122]

good questions, but i have no idea. i don't think this is within the scope of the MCAT so you shouldn't worry too much about it. the answers to your questions, if it came up on the test, would be in a passage.

 

[MT Headed]

So the Earth spins around an axis... so it has torque.

The earth doesn't have torque, it has angular momentum.

L = Iw

The I of earth is enormous, the w is kind of small (2 pi radians / 8.64 x 10^4 seconds), and the L is enormous.

Objects moving linearly can have angular momentum about an axis too (L = mvr). If enough small particles collected together and the net angular momentum of all of the particles was counterclockwise as viewed from above the north pole, then the resulting earth would also have the same angular momentum. In the absence of an external torque, angular momentum is conserved.

I have no idea if the earth really was created this way.

 

[salim271]

The earth doesn't have torque, it has angular momentum.

L = Iw

The I of earth is enormous, the w is kind of small (2 pi radians / 8.64 x 10^4 seconds), and the L is enormous.

Objects moving linearly can have angular momentum about an axis too (L = mvr). If enough small particles collected together and the net angular momentum of all of the particles was counterclockwise as viewed from above the north pole, then the resulting earth would also have the same angular momentum. In the absence of an external torque, angular momentum is conserved.

I have no idea if the earth really was created this way.

Ah yeah when I googled it I came across angular momentum but i didnt realize that it was a phenomenon different than torque. Thanks lol.

I really dont understand angular anything, I have to study it even if EK insists its not important, it comes up a lot...