Centrifugal force: centrifugal force is an imaginary force that has been misunderstood for a long time, that is, inertial force. Because we can't find the object that applies force, we deviate from Newton's third law. When an object moves in a circle, centripetal acceleration will produce a force-like effect in the coordinate system of the object, which is similar to a force acting in the centrifugal direction, so it is called centrifugal force.
When an object moves in a circular motion, that is, it does not move in a straight line, that is, it moves in a non-Newtonian environment, the force that the object feels is unreal.
Calculation formula of centrifugal force: f = mv * v/r (m stands for mass, unit kilogram v stands for speed, unit meter per second, and r stands for centrifugal movement radius, unit meter. )
Application of centrifugal force:
The first is the meteor hammer.
Meteor hammer is a soft weapon made by tying a metal hammer to one end or both ends of a long rope, and it also belongs to the category of hidden weapons. There is only one hammer, and the rope is about five meters long, called "single meteor"; Tie two hammers, the rope is four and a half feet long, which is called "double meteor". Its hammer is melon-shaped, polygonal and round, as big as a duck egg. There is an elephant trunk eye at the tail of the hammer for stringing together. In modern martial arts, double shooting stars are practiced, mainly by holding the middle part of the rope, performing vertical dancing, lifting flowers, one-handed flowers, chest and back flowers, waist wrapping, neck throwing and so on. The flower method is the same as stick flower and broadsword flower.
Second, centrifuges.
Centrifuge is a special instrument for separating and precipitating mixed liquid (including solid) by centrifugal force. The commonly used electric centrifuges in the laboratory include low-speed and high-speed centrifuges, low-speed and high-speed freezing centrifuges, and overspeed analysis and preparation dual-purpose freezing centrifuges. Among them, low-speed (including high-capacity) centrifuges, high-speed centrifuges and high-speed freezing centrifuges are the most widely used, and they are indispensable tools for separating and preparing biological macromolecules in biochemical laboratories.
Third, the tea paradox
The paradox of tea describes the phenomenon that tea leaves swim back to the center of the cup bottom after being stirred in the cup, rather than being pushed to the edge of the cup bottom by spiral centrifugal force as expected. The original explanation comes from a paper by Albert Einstein (1926) explaining the problem of river bank erosion (Bayer's law). Stir the liquid to make it rotate in the cup, resulting in outward centrifugal force. The liquid near the outside of the bottom slows down due to the friction of the cup wall, where the centrifugal force is weakened, so the pressure difference has a greater effect on the water flow than the centrifugal force. This is called the boundary layer, or more precisely the Ekman layer. Due to centrifugal force, the force along the edge is greater than that in the middle. If all liquids rotate as solids, the internal centripetal force is related to the external (centripetal force) and the rotation speed, so there is no inward or outward movement. In a teacup, the bottom rotates slowly, resulting in a pressure gradient and an inward wave flow along the bottom. Up, the liquid flows outside. The second wave flows inward along the bottom, collecting the tea leaves outside the edge to the center. Because the weight of tea can't rise, it stays at the bottom center. Combined with the first rotating wave, these tea leaves will spiral inward along the bottom.