How to Win the Wishbone Game at Thanksgiving, Through Physics

Every year at Thanksgiving, my brother and I have this tradition of breaking the wishbone of the turkey from last year's Thanksgiving. Whoever gets the larger part of the wishbone then gets to make a wish. This tradition actually dates back to the Ancient Romans as they were the first to consider the bone lucky. Now this tradition has slowly changed over the course of history to include the turkey wishbone as well, making it the perfect Thanksgiving tradition. In case you don't know what the bone I'm talking about is, here's a picture of it:

 

The wishbone is the forked chest bone in birds where the two clavicles are fused together. It is very symmetrical in shape and might make you assume that the bone is likely to snap in half if equal force is applied to either side. Now, this almost never happens. My brother and I have never snapped a wishbone perfectly in half and physics can explain why. Physics is actually the key to winning this game. So let's look at two very important equations:

Pressure= Force/Area

Torque= rFsin(theta)

Pressure is ultimately what causes the bone to break, so the first equation is important to consider when choosing which side of the bone you want. Assuming my brother and I apply equal amounts of force to each side of the bone, the side with the greater area would have less pressure. Based on this, in order to win, you should choose the side of the bone that is slightly thicker as it would have a greater area and therefore, less pressure would be exerted on it. However, it is unlikely that my brother and I would apply the same force to the wishbone as he is significantly stronger than I am. Because of this, he most likely applies more force to his side of the wishbone than I do. So in order to win, all I have to do is let him pull more than I do and the pressure on his side will exceed mine due to the greater force applied, causing his side to snap. 

Understanding torque also helps to win this game. In the torque equation, r represents the distance from the axis of rotation. In the wishbone, the axis of rotation is the middle point of the bone. Knowing this, situating your hand closer to the center of the bone will minimize the torque on the bone and minimize the force applied as torque is directly related to force. Less force will result in less pressure and decrease the likelihood of the bone breaking on your side. If you were to put your hand at the very bottom of the bone and apply force there, the torque would be much higher because the distance from the axis of rotation is higher and would result in the bone snapping on your side. 

So turns out that you don't really need luck at all to win the wishbone, you just need physics! 

Disclaimer: I haven't actually tested out any of these tips so I can't guarantee a 100 percent success rate. 

For more information on wishbones and the physics behind it:

https://www.southernliving.com/thanksgiving/how-to-win-the-wishbone

https://modernfarmer.com/2014/11/whats-story-wishbone/

https://www.thekitchn.com/what-is-a-wishbone-and-why-do-we-crack-it-ingredient-intelligence-213029