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.
Landforms of fluvial erosion and deposition. Oxbow lakes and meanders are found in the middle course of the river (long profile) and are formed as a result if erosion and deposition. The formation of meanders leads eventually to the development of oxbow lakesVideo showing the features of the middle course of the River Tay -. http://www.bbc.co ....