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.
The 3 landforms created by wave erosion sometimes called coastal  erosion are headlands and bays, cliffs and wave cut platforms and  finally caves, arches, stacks and stumps â¦ . Wave erosion is the  wearing away of land and the removal of beach by wave currents.
1 These areas are eroded at a faster pace creating a hole through times by the process of erosion and wave action it becomes a cave. 2  A stack is formed when a headland is eroded by wave and wind action. 3  A stump is the landform formed when a stack is eroded leaving a small piece of rock visible at high tides.