What causes the contracting nebula to flatten into a spinning, pancake-like structure called a protoplanetary disk?

Answer

Centrifugal forces due to the conservation of angular momentum

As the nebula contracts, its rate of rotation increases due to the conservation of angular momentum. This rotational speed generates centrifugal forces that cause the cloud to flatten perpendicular to the axis of rotation into a spinning disk.

What causes the contracting nebula to flatten into a spinning, pancake-like structure called a protoplanetary disk?

#Videos

Formation of the Planets - YouTube

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