Why does the high speed clockwise rotation of the wheel look like a slow counterclockwise rotation?
Simply said is the result of the lack of sampling, the human eye is a sampler. The relationship between the sampling frequency and the rotational speed of the wheel. Draw a spoke on a rotating disc, illuminate with a regular flashing light. If the light flicker is large enough, you can know the speed of rotation correctly, but if it is too small, the position of the spoke you see may be a few turns After the cycle of the location, if there is a sample in the previous, there will be the illusion after the turn.
The wheel in the movement of the fast, resulting in the back of the auxiliary cover in the previous blur, can be captured by the human eye. As the original blur is itself in the movement, so the human eye is to see the slow movement
The highest rate observed by the eye is 0.02 s, that is, if an object does not coincide with its final position and the final velocity within 0.02 s, the human eye does not see the object (although the film is Picture, but because each picture between the conversion speed is greater than 0.02s each, so it does not seem to Carton,
