Wheels spinning backwards answered

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Thread: Wheels spinning backwards answered

  1. #1
    Join Date
    Dec 1969

    Default Wheels spinning backwards answered

    I&#039;m here thumbing through my Maxim mag, and I remember a while back someone asked why wheels appear to spin backwards... lotsa tech answers, but here&#039;s maxim&#039;s answer:<BR><BR>Q&#062; Why do car wheels sometimes appear to be rotating backward?<BR><BR>Either the car is backing up - har har - or you&#039;re seeing a stroboscopic effect, i.e., you&#039;re watching the spinning wheels under intermittent light. You&#039;ll notice it around most streetlights, which actually turn off and on about 60 times per second, and it&#039;s extremely common on film (24 frames per second). "This illusion occurs when the wheel revolves at a rate that is inconsistent with the rhythm of the fixed light rate", explains Bob Hirshon, host of Science Update Radio. Let&#039;s say you&#039;re watching Knight Rider, and K.I.T.T has a spot of hollandaise sauce on his hubcap. Unless K.I.T.T&#039;s wheels rotate exactly in sync with the strobing --i.e., time the flash occurs -- the glob will appear to move clockwise or counterclockwise, depending on the wheel&#039;s turning speed, giving the illusion of a slowly turning (backward or forward) wheel. And presto! You&#039;re a hit-and-run victim.<BR><BR><BR>I&#039;ll have to find the answers that were given here to see how close they were now :)

  2. #2
    Join Date
    Dec 1969

    Default I think Craig was pretty much......

    Spot on!<BR><BR>http://www.aspmessageboard.com/forum/showMessage.asp?F=40&M=498642&P=1

  3. #3
    Join Date
    Dec 1969

    Default ...too goddamn intelligent.

    Or a smart-alec git, either way.<BR><BR>:-)<BR><BR>I guess doing physics at A-level has some perks. Not many, though. In fact, that&#039;s the first. :-)<BR><BR>Craig.

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