The process of coin flipping

euro-84830During coin flipping the coin is “flipped into the air”, i.e., caused to both rise and rotate about an axis parallel to its flat surfaces. Typically, agreement is reached that one person will explicitly assign the action that will ensue from one positioning of the coin, and another, presumed to have the opposite interest or to be impartial, performs the following steps:

  • resting the coin on the sides of several segments of the bent index finger of the dominant hand,
  • pressing the tip of the bent thumb of the same hand against the palm-side of the index finger, so that friction there holds the thumb back from extending further,
  • tensing the muscles that extend the thumb, thereby storing energy in the form of tension in those muscles,
  • further extending the thumb and/or slightly uncurling the index finger, thereby overcoming the finger’s frictional grip against the thumb-tip so it slips, and freely and rapidly extends, with it or its nail
    • hitting the bottom face of the coin, centered within the half of the coin that is less in contact with the bend index finger, and thus
    • simultaneously pushing it more or less upward and setting it rotating around an axis parallel to the circular faces of the coin;
  • optionally, suddenly raising and quickly stopping the hand involved, in coordination with the releasing of the thumb, thus imparting extra vertical momentum (but little additional rotary momentum) to the coin. (Depending on the skill of the coin-tosser, and any resulting horizontal motion, the optional upward jerk of the tossing hand may be needed to ensure the coin stays aloft long enough to get the catching hand into position, or for the tosser and observers to move out of its path.);
  • saying “Call it”, to alert the party so designated to say (while the coin is in motion, though now it is preferable to call before the coin is tossed, see Phil Luckett) either “Heads” or “Tails”, designating the outcome that will correspond to the previously agreed upon outcome;
  • once it falls back to a convenient height, either
    • catching the coin in an open palm, or
    • bringing one hand down over it, to prevent its bouncing away, as it lands on the other hand or arm, and quickly removing the upper hand from it, or
    • avoiding interfering with it as it falls onto a sufficiently smooth and uncluttered point on the ground;
      • if the coin falls to the ground, despite an attempt by the person flipping the coin to catch it, the process is usually not repeated, and
  • all those involved jointly observing whether it has landed “showing heads” — with the side bearing the portrait or profile uppermost — or “showing tails”.

There may be several rounds in a single game of coin flipping if the participants agree to this ahead of time, but typically there is only one; this keeps the contest quick and prevents the losing side from asking for more rounds after the toss.

The coin may be any type, as long as it has two distinct sides, with a portrait on one side. The most popular coin to flip in Canada and the United States is the quarter because of its size; in the UK a 2p, 10p or 50p piece is favoured. However, participants will use any coin that is handy.

Licensed under the GNU Free Documentation License. It uses materials from the Wikipedia.

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