Why is it when a car, lets say a ferrari! when under hard excelleration the wheels look like they spin backwards! what causes this??? I know I am not the only that see this! am I ?
Assuming you are talking about a film or tv playback, and NOT viewing the action eyeball live. TV or movie cameras do not record continuously but record a picture roughly every 16 (or 32) milliseconds. Consider recording a car whose wheel rotates before the next picture is taken. If the wheel rotates 2 degrees between pictures, it would look to be rotating smoothly. Even if it rotated 362 degrees or 722 degrees it would appear to be rotating 2 degrees. Lets say the wheel speeds up to rotate 355 degrees (just less than one complete revolution) between pictures you would have a situation where the wheel, although rotating forward properly, would actually appear to rotate backwards. Of course, as the car accellerates, all matter of intervals become recorded, resulting in a forward look, then backward, then forward again. Are you able to visualize this OK? If not, head for a disco with a battery powered fan. Strobe lights are used in the lab and in disco type dance halls. It's really fun to play with a strobe at night and watch someone walk or perform all manner of gyrations. enjoy
It is an optical illusion based on the position our brains "see" the spoke. Here is a mental experiment you can do. Imagine a clock on the wall that has a second hand. Now imagine it is on the 5, close your eyes for 5 secs and the second hand will be on the 6, close your eyes again for 5 seconds again and it will be on the 7 and so on. Now imagine that the second hand is on the 5 but you close your eyes for 55 seconds. When you open your eyes, it will be on the 4! So your brain "sees" the second hand going backwards. Since wheels are spinning faster than clocks our eyes and brains catch and focus on the spokes at positions that seem to make them move backwards.
