How Does Shrinking Affect the Rotation Speed of a Planet?

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The discussion centers on how the shrinking of a planet affects its rotation speed, specifically using Planet A as an example. The key concept is the conservation of angular momentum, which states that as the radius decreases, the rotation speed must increase to maintain momentum. The participant initially struggled with calculating the new angular velocity but ultimately found a solution using the relationship between velocity and radius. They applied the formula V1 x R1 / R2 = V2 to determine the new velocity after the planet's size reduction. The conversation highlights the importance of understanding angular momentum in planetary dynamics.
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Homework Statement



Planet A (at X meters) completes 1 full rotation (Y sec). Planet A then shrinks to (X2 meters)
What is its rotation speed now.
Conservation of angular momentum


Homework Equations


T=2pi/w
W=V/r


The Attempt at a Solution


I found how to reverse engineer the whole system but I'm unable to calculate w for a reduced radius.
 
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What's the formula for calculating angular momentum?
 
SOLVED!
I used V1 x R1 / R2 = V2 then used the velocity of V2 against the circ of Planet A's new radius to give the answer, yipee!
 
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