= Sufficient escape condition for a translating trap
{title2=$v_T>\sup(F/\zeta)$}
In the trap frame, a particle under <linear drag> has relative speed $F(y)/\zeta-v_T$. A uniform strictly negative relative speed guarantees finite passage through a <compact support>. For a bounded continuous force, $v_T>\sup F/\zeta$ supplies that condition. For ordinary smooth forces, an encountered zero of the relative speed is an equilibrium or a passage bottleneck, not a finite crossing. Negative forces do not impede forward trap passage.
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