Skill 5 of 8
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Angular momentum conservation

Just like we have a linear momentum conservation law telling us how the sum of all momentum never changes (the same before and after any impact), $\sum \vec p_\text{before}= \sum \vec p_\text{after}$, we also happen to have the equivalent angular momentum conservation law:[1]

$$\sum \vec L_\text{before}= \sum \vec L_\text{after}$$

This law explains how the ballerina spins faster by pulling her arms in, and how the gymnast can spin fast enough to make a backflip by pulling arms and legs in.

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  1. Conservation of Angular Momentum’ (web page), Lumen Boundless Physics, 2017, courses.lumenlearning.com/boundless-physics/chapter/conservation-of-angular-momentum (accessed Feb. 27th, 2020)