The biggest irony is not being able to rely on search engine results because it’s just explanations about why sound moves faster in a liquid and not any answers to your question, only to ask on Lemmy and have people explain why sound moves faster in a liquid and not give any answers to your question.

Might help to look up the definition of Terminal Velocity.

Terminal velocity is the maximum speed an object can reach while falling through a fluid (like air or water). It occurs when the force of gravity pulling the object down is balanced by the fluid’s resistance, or drag, pushing it up.

As the speed of an object increases, so does the drag force acting on it, which also depends on the substance it is passing through (for example air or water). At some speed, the drag or force of resistance will be equal to the gravitational pull on the object. At this point the object stops accelerating and continues falling at a constant speed called the terminal velocity (also called settling velocity).

Ahhh in terms of fluid flow? I mean you can move a glass of water as fast as you want (don’t @ me physicists) if the glass is moving at that speed.

Assuming this is flow.

Let’s think about a 1 metre long pipe full of water. Let’s make the water start flowing though this pipe by pushing through the water at the start of the pipe. Now as water enters the pipe, water at the other end of the pipe exits. But there’s a time delay between the first new water that enters the pipe and the first water to leave the pipe. (I can explain this further if needed) That time delay is the time it takes the speed of sound in water to travel through the 1m pipe.

Now let’s consider water moving faster than the speed of sound in water entering the pipe. It’s moving so fast through the pipe that it actually reaches the end of the pipe before the water at the end of the pipe has had enough time to move out of the way. Here flow is effectively dead and the water isn’t really flowing though the pipe anymore, it’s just being pushed through by whatever is moving the water in the first place.

At the end of the day it’s semantics, you could define flow as being “water moving through a pipe” and in that case yeah, water can “flow” at whatever speed you want if you push it hard enough. Typically though, flow means a steady and consistent stream of fluid. And at supersonic speeds, that stream is anything but steady and consistent.

Sound is transferred through a medium literally as a wave. When you get right down to the core of it, the wave requires movement within the medium to transmit.

So it might help to conceptualize it not as “Liquid cannot move faster than the speed of sound in it’s medium” but more like “The speed of sound in a liquid medium is defined by the speed at which energy can propagate in that system, which includes motion.”