A centripetal force (from Latin centrum center and petere to seek) is a force that makes a body follow a curved path. Its direction is always orthogonal to the motion of the body and towards the fixed point of the instantaneous center of curvature of the path.
There are a number of things that can cause a whitish coating or white spots to develop on the tongue, including the f ollowing: 1  Leukoplakia. 2  Oral thrush. 3  Oral lichen planus.
A black or brown tongue typically is due to the overgrowth of bacteria that normally are present on the tongue. This, too, can be caused by the killing of some bacteria with antibiotics so other bacteria overgrow. But the most common cause of discoloration of the tongue is the overgrowth of a fungus. The most common fungus is called candida. But overgrowth of the candida fungus turns the tongue white. Infection with candida is called candidiasis, and when it happens on the tongue the condition is called thrush.