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The wagon-wheel effect (alternatively called stagecoach-wheel effect) is an optical illusion in which a spoked wheel appears to rotate differently from its true rotation. The wheel can appear to rotate more slowly than the true rotation, it can appear stationary, or it can appear to rotate in the opposite direction from the true rotation ...
A wheeled buffalo figurine—probably a children's toy—from Magna Graecia in archaic Greece [1]. Several organisms are capable of rolling locomotion. However, true wheels and propellers—despite their utility in human vehicles—do not play a significant role in the movement of living things (with the exception of certain flagella, which work like corkscrews).
Wheels can also lose traction when surface conditions reduce available traction such as on snow and ice. As an open differential delivers only enough torque to cause the "weakest" wheel to spin, if one drive wheel is stationary on a low traction surface (mud, ice, etc.), the deliverable torque is limited to the traction available on it.
Topspin in ball games is defined as spin about a horizontal axis perpendicular to the direction of travel that moves the top surface of the ball in the direction of travel. Under the Magnus effect, topspin produces a downward swerve of a moving ball, greater than would be produced by gravity alone.
They can be read right side up or upside down, or both. Rotation ambigrams are the most common type of ambigrams for good reason. When a word is turned upside down, the top halves of the letters turn into the bottom halves. And because our eyes pay attention primarily to the top halves of letters when we read, that means that you can ...
Penguin books in Australia recently had to reprint 7,000 copies of a now-collectible book because one of the recipes called for "salt and freshly ground black people." 9 misprints that are worth a ...
The first is not an in-camera effect, but is achieved by printing the film backwards in an optical printer, starting from the final frame and working to the initial one. (This requires a true optical effect, since simply playing the film in reverse when exposing it onto a new negative causes it to come out upside down.) [ 11 ] [ 12 ]
Burnout in the box at Tarlton International Raceway, South Africa Fire burnout, Santa Pod Raceway, UK. The origins of burnouts can be traced to drag racing, where they have a practical purpose: drag racing slicks perform better at higher temperatures, and a burnout is the quickest way to raise tire temperature immediately prior to a race.