Question

what is the angular physics behind stretching arm during rotation​

Answer 1

Answer:

Why does Earth keep on spinning? What started it spinning to begin with? And how does an ice skater manage to spin faster and faster simply by pulling her arms in? Why does she not have to exert a torque to spin faster? Questions like these have answers based in angular momentum, the rotational analog to linear momentum. By now the pattern is clear—every rotational phenomenon has a direct translational analog. It seems quite reasonable, then, to define angular momentum L as

L = Iω.

This equation is an analog to the definition of linear momentum as p = mv. Units for linear momentum are kg ⋅ m/s while units for angular momentum are kg ⋅ m2/s. As we would expect, an object that has a large moment of inertia I, such as Earth, has a very large angular momentum. An object that has a large angular velocity ω, such as a centrifuge, also has a rather large angular momentum.

Explanation:

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