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A flexible pencil???



Why does a pencil or any linear object look like it is bending when you wiggle it? I was very curious of this today and was wondering why? The answer to this question is that in the way you are wiggling it you are rotating around its center in such a way that our eyes perceive that the ends of the pencil is moving faster even though the angular velocity is truly the same through out because it is truly a rigid object. The reason for this is because when an eye is viewing a fast-moving object the formed image can be modeled as the image of points that appear to have different velocities on the same object. The reason our eyes do this is the same as when transitioning front light to dark. It takes time for our eyes to focus and adjust to our surroundings so by our eyes focusing on the fulcrum or our fingers in this case, it cases it ends to blur.

  Image result for rubber pencil


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Optical illusions are always fun, but keep in mind that the pencil may not be completely rigid, and therefore could bend slightly. Probably not enough for the naked eye to detect, though.

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