An actively driven cell reaches steady speed when its drive force exactly cancels the drag, leaving zero net force. The active drive 12 N matches the checked drag 12 N, giving net force 12 + (-12) = 0 N exactly for the stated toy force ledger; real cells have variable drag, nonuniform media, stochastic forcing, tracking limits, and calibration uncertainty.
A balanced active drive can hold one checked terminal state. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.
highlighted = computed this step
Put drive and drag on one axis
The active drive is 12 N and the checked drag is 12 N.
12N12N
Equal drive and drag leave zero net force
The net force is 0 N in this balanced training case.