Phil Plait, Bad Astronomy Blog
A good example of the conservation of angular momentum is to think of a figure skater. When the skaters spin on their skates with their arms outstretched, the skaters spin slowly. As they bring their arms in closer to their bodies, the rate of spin increases. To keep the same angular momentum, the angular speed must increase as the outmost portion of the rotation decreases.
Angular Momentum
L = R*ωwhere
- L is the angular mometum, which is the same for the left and right pictures above
- R is the distance from the center of spin to the outermost portion of the body spinning (this is shown as I above with is actually the moment of Inertia around the center of spin)
- ω is the angular speed, i.e. how fast the angle is changing over time.
The rest of the cloud is now free to consolidate into planetessimals, freeing up the area around their orbits. The inner part of the solar nebula contained mostly refractory elements, leading up to more dense planetessimals and the outer part contained a lot more volatile elements, leading to planetessimals that were both rocky and icy. As the planetessimals starting colliding with each other, they stuck together, melting, and allowing the heaviest elements to sink to the center of the bodies. As more and more planetessimals collided, the bodies grew bigger and bigger, getting to a point where the bodies were able to form spherical shapes, and leading to the planets we see today.
No comments:
Post a Comment