system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5 the physics of playground swings.

While I understand (intuitively, if not scientifically) how pulling on the chain might affect my movement, the fact that I can *just* move my legs in the traditional extended-when-moving-forward, bent-when-moving-backwards way and gain momentum makes no sense to me.
gpt
While you move your legs, you move your center of mass (thats a point where the gravity pulls you down) in front of or behind the seat. The center of mass "wants" to be as close to the the ground as possible and so by changing where the center of mass is you start moving.