Basically, a passive radiator is a reactionary device as the name suggests. When a driver (such as a subwoofer) is mounted to a sealed speaker box (enclosure), the physical forward/back movement of the speaker affects the internal air pressure of the enclosure.
Three landforms created by wind are; sand dunes, yardangs (half-teardrop shaped formations hill sized, and deflation hollows (wind swept depressions.
Coasts of Erosion. Coasts of erosion form as a result of high energy waves, large fetch, high exposure and limited deposition. They are also associated with drift alligned coasts that are influenced by longshore drift. This transfer of sediment along the coast limits the development of beaches and leads to greater cliff exposure, hence cliff retreat.