xkcd #3111: Artificial Gravity
Title text:
Low gravity can cause bone loss, so we're pleased to report that, since we initiated capsule motion, the number of bones in each crew member has been steadily increasing.
Transcript:
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Source: https://xkcd.com/3111/
Literally the artificial gravity on surface ships. Sometimes, if you time it just right, you can float up 7 stairs or completely miss your bunk.