alrite-when you look at a video of a car you can sometimes see the wheels going backwards as the wheel rotates more than 180 degrees for the time between each frame. could the same not happen for your eyes? i.e. you see a car going so fast that the wheels look as if they're going backwards? as your brain works with the same method as the T.V., just a lot faster-doesn't it?...😛
Originally posted by geniusIt does happen...
alrite-when you look at a video of a car you can sometimes see the wheels going backwards as the wheel rotates more than 180 degrees for the time between each frame. could the same not happen for your eyes? i.e. you see a car going so fast that the wheels look as if they're going backwards? as your brain works with the same method as the T.V., just a lot faster-doesn't it?...😛
I vaguely remember something about this, that TV only needs 24 picture per second to fool the eyes because they receve 20 images per second. I could be misremembering.
Wheels with spokes are especially good at deceaving us because the whole wheel doesn't have to go around before your eye can register it, the spoke just has to have travelled past where the next one was (if that makes sense)
Here's a good explaination (found at: http://www.newton.dep.anl.gov/askasci/gen01/gen01119.htm):
"This effect is called the "stroboscopic effect" and it is most pronounced
in movies, especially older ones, but it also occurs with you naked eye.
Your eye's response time is about 1/15 sec. to 1/30 th sec. if the rotating
blade's angular velocity exactly matches that response time each revolution
would superimpose the previous one and the blade would appear to stand
still. If it is a little slower, the blade doesn't quite make it to the
point of superposition and the blade seems to be going backwards slowly. If
the blade is moving a little faster than superposition then the blade
appears to advance slowly. If the frequency of rotation is very different
then the effect disappears, until the frequency approaches 2X the response
time, when superposition occurs twice every revolution.
You could research the topic of "strobe lights" on the Internet for a more
detailed discussion. Strobe lights, which flashes a short spike of light at
an accurately determined interval, are used to measure the revolutions per
min (or sec.) in industrial and technological applications.
Vince Calder"
