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.
That made him smile. Dad said, 'There are several agents of erosion that occur. Water can be one of the most effective and efficient modes of erosion. Waves, for instance, can cause changes in landforms by weathering the surrounding rocks and forming a beach by eroding the debris and depositing it on the shore. As the waves slowly wear down the rocks, the bits of rock turn into sand, which is a size of a rock piece.