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rack, wrack

NGS preferred usage:  As a noun or verb rack is associated with pain, torment, or twisting and straining, and with any sort of framework, including the instrument of torture:
            Roger confessed on the rack
            nerve-racking trip
            rack one's brains

As a noun or verb wrack is associated with wreckage or destruction:
            wrack and ruin
            storm-wracked coast
            wind wracked the vessel