The medical name for blood in the urine is haematuria. If blood in the urine is obvious with the naked eye, it is called macroscopic, or visible haematuria. If the blood can only be detected with laboratory testing, it is called microscopic, or non-visible.
This is not a new kind of force; it is merely force as applied in circular or rotational motion, and it is absolutely essential. Hence, physicists speak of a centripetal force requirement: in the absence of centripetal force, an object simply cannot turn. Instead, it will move in a straight line.
The friction force is the force exerted by a surface as an object moves across it or makes an effort to move across it. There are at least two types of friction force - sliding and static friction. Though it is not always the case, the friction force often opposes the motion of an object. For example, if a book slides across the surface of a desk, then the desk exerts a friction force in the opposite direction of its motion.