tōpana pā
1. (noun) contact force.
Ko te tōpana pā: Koia nei te tōpana ka hua ake i te pānga rawa o tētahi mea ki tētahi. Hei tauira, ko te whana pōro, ko te tukinga motukā (RP 2009:410). / Contact force: This is the force that results from the actual contact of one thing against another. For example, kicking a ball and bumping a car.