I'm sure you've seen it. You'll be driving down the freeway and notice the the wheels on the car next to you seem to be spinning in the opposite direction. I know it's an illusion, but why does it happen?
Tags: freeway, illusion, wheels
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on Friday, February 19th, 2010 at 3:40 am and is filed under car wheels.
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February 19th, 2010 at 3:40 am
This is a stroboscopic effect which happens when you are seing repeated images of the tire. This can happen if you see the tire on film (often 24 frames a second) or on a TV or lit by an AC electric light or any process which regularly breaks up your image of the tire, such as looking through a fan at the tire.
Normally the eye will interpret the sucessesion of rotated images of the tire as the tire rotating because each image has rotated a little further than the previous one.
If the tire is rotating quickly enough that by the time you see the next image of the tire, it has rotated so much that patterns on the tire are slightly backward from the previous image, (for example, maybe it made 99% of a turn), then what you are seeing is exactly the same as it would look if the tire really was moving backwards and so that is what you see.
February 19th, 2010 at 3:40 am
because you are a homosexual
February 19th, 2010 at 3:40 am
I think because of the speed of the car next to you, but mostly because of the brain and eye lack of capacity to process so many frames at once…
Don’t know for sure though…
February 19th, 2010 at 3:40 am
Voyager21′s explanation is very close. The only difference is that the human eye is only capable of processing approximately 12 frames per second. The speed at which you will see this will vary according to the diameter of the wheel and the number of "spokes" on the wheel because of the repeating pattern. This same principal is why the cheap japanese cartoons appear to be very jerky. They only print around 10-11 frames per second. They must have known we would be gullible enough to accept it.