system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: When you're on a roller coaster or something which drops quickly, what is the feeling in your stomach and why do you get it?
gpt
That feeling is two things. One - you have special sensory cells that detect acceleration. These feel rapid acceleration and essentially cause a panic response.   


The other part of it is more visceral - literally all your organs are moving and you feel it.