From where did our earth get its initial velocity ?

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Discussion Overview

The discussion revolves around the origins of Earth's initial velocity in its orbit around the Sun, exploring concepts related to angular momentum, the formation of the solar system, and the dynamics of protoplanetary disks. It touches on theoretical explanations and the mechanics of planetary motion.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants suggest that the conservation of angular momentum during the collapse of an interstellar gas cloud is key to understanding Earth's initial velocity.
  • One participant questions how the rotation of the planet relates to its revolution around the Sun, indicating a need for clarification on the connection between these motions.
  • Another participant argues that the mechanism for rotation and revolution is fundamentally the same, applying to the entire solar system rather than just individual planets.
  • There is a suggestion that the random movements of dust and gas in space contribute to a net rotation as material collects towards a center, which can lead to increased speeds as the material collapses.
  • One participant posits that the initial conditions of the universe, such as those stemming from the Big Bang, could be considered the ultimate source of momentum for all particles, including Earth.

Areas of Agreement / Disagreement

Participants express varying levels of understanding and agreement regarding the mechanisms of rotation and revolution, with some confusion noted. Multiple competing views on the relationship between these concepts remain, and the discussion does not reach a consensus.

Contextual Notes

Some participants express uncertainty about the relationship between planetary rotation and revolution, indicating that further clarification may be needed. The discussion also touches on complex dynamics that are not fully resolved.

Who May Find This Useful

This discussion may be of interest to those exploring astrophysics, planetary formation, and the dynamics of celestial bodies, as well as individuals curious about the fundamental mechanics of motion in the universe.

Sab95
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I read in a article that Earth revolves around the sun at speed of 30km/s but from where did it get its velocity at the beginning..?
 
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From the conservation of the angular momentum.

As the interstellar cloud of gas collapses to form a protoplanetary disk, random motions of the molecules do not perfectly cancel out, causing the emergence of a preferred spin direction in the macroscale. Further collapse exaggerates this initial preferrence, as any initial angular momentum has to be conserved in a closed system.
This is also the reason why all planets revolve around the sun in the same direction, and have generally the same direction of rotation on their axes.
Although in that last case there's obviously more at play than that. Just look at Venus or Uranus.
 
@Bandersnatch :

But how that could account into the revolution of planets.. its something related with the rotation of the planet.. how is it related with the revolution..?? that's the part i can't understand..
 
I'm not sure where lies your confusion. It's the same mechanism. Only instead of the scale of a single planet it's the whole solar system.

Here's a video showing the simulation of the process:


and the paper from which it's sourced:
http://arxiv.org/abs/1010.1489
 
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Your question implies that you think it is strange that the rotation is not exactly 0. Wouldn't it be more strange for the rotation to be exactly a predetermined number, like 0?
 
The material the Earth is made of was flying around in space. Dust and gas has some random movement, something had pushed it a little etc or it just happened to move some way since the last place it came from. When it starts collecting toward some center, it is likely that it has some small net rotation around the center, ie it is not likely that for every piece of dust going one way there is one going the other way, there is some imbalance. The falling towards the center makes them speed up and the effect gets exaggerated. You may be aware of the skater speeding up when the arms are pulled in effect, which also happens with the collapsing dust.
 
yup.. now i got it.. pls stay tuned for further questions..
 
If you want to go back even further, the ultimate source for any momentum of any particle is, of course, whatever caused the big bang.
 

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