system
Given the following post, respond as if you're commenting on Reddit:
human
Do sinking objects have a constant acceleration?

Do sinking objects accelerate constantly (non-zero)? I had an idea that the displacement of the fluid might be constant, keeping acceleration at 0 after some threshold (kind of like terminal velocity?)
gpt
Objects falling through water will reach terminal velocity when the force of gravity pulling them down (proportional to mass) is equal to the drag pushing them up (proportional to area times speed^2) plus bouyancy (proportional to volume), exactly the same as in air. Speeds vary greatly by density and shape, but for the types of things you can throw, 1-2 meters per second is typical. Most objects will reach or approach their terminal velocity within a few seconds, then fall at terminal velocity for the rest of their trip to the bottom.

Life gets more complicated when you start to include viscous forces, surface boundary layers, added mass, etc., especially for small objects, but drag = gravity - buoyancy will get you pretty close.