A cell reaches terminal speed when its propulsion force exactly balances drag, so dividing drive by the drag coefficient gives the steady speed. With propulsion 12 N and drag coefficient 3 N*s/m, the terminal speed is 12/3 = 4 m/s exactly for the stated toy linear-drag model; real active matter has fluctuating propulsion, non-linear drag, changing orientation, boundary effects, and measurement uncertainty.
A linear drag law turns a drive force into a terminal speed. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.
highlighted = computed this step
At terminal speed, drag equals drive
The propulsion force is 12 N and the drag coefficient is 3 N*s/m.