5 ms·
Consider a coin which consists of a strip along one side made of a dense metal, and the remainder made of a light metal. This would move the center of rotation
by kevinpet 11y ago
Consider a coin which consists of a strip along one side made of a dense metal, and the remainder made of a light metal. This would move the center of rotation to the side of the coin. Now place the coin on your forefinger with heads up and the heavy band facing away from you. Assuming the rate of rotation was high relative to the falling rate of the coin, then it will tend to first impact the surface with the leading edge of the light two thirds, face down.
The article makes assumes that conservation of momentum guaranteeing a constant rotation rate guarantees fairness. But this relies on the assumption that biasing the coin cannot affect the timing of when it lands.
Of course, this doesn't bias the coin in either direction, it just lets the flipper choose which way to bias a particular flip.
- scott_s 11y agoThis paper assumes that the coin is caught.
- Retric 11y agoIn that case you don't need to bias the coin, you can flat out learn to do a normal looking coin flip with catch and get a biased result.
- YokoZar 11y agoOr decide whether or not to flip it by putting it on top of your other hand depending on how it landed when you caught it.
- seanp2k2 11y agoPut something on one side of the coin so you can feel what side is up and decide to flip it.
- baxter001 11y agoThat's not biasing the coin itself though, it's rigging the whole flipping procedure. If I toss a fair die and catch it in mid air with a robotic arm and high-speed camera so that I always catch it with the two face on top, it's still an unbiased die.
- cmsmith 11y agokevin_pet's coin would still be biased if it were caught. The article contends that you can bias the bouncing part of a coin flip, but not the falling part - GP proposes a coin with a biased falling motion.