system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How does a boomerang work?
gpt
You throw the boomerang vertically, and spinning quickly. The boomerang, overall, has lift like a wing, which pulls it sideways. But because it is spinning, the top of it is moving faster, so has more lift, than the bottom. You might think that this would pull the boomerang over on the top. But spinning things don't work like that.

When a force is applied to a spinning object, it does not turn in the direction of the force, but in the direction 1/4 turn 'later' than where the force is applied. So instead of tipping over, it turns about the vertical. So it rotates, turning about the vertical. The lift keeps pulling the boomerang sideways, which, as it is slowly rotating, pulls the boomerang in a circle.