In the winter, my favorite outdoor activity is snowboarding and sometimes, I get a little too reckless. However, this post will go through the physics of a simple 360 in the air on a snowboard, which can be applied to skis as well. 

The first important part in landing a 360 is making sure you can hit the jump with the perfect speed to clear the "table" part and land on the actual landing. This is critical because if you under/undershoot the landing, you will most likely fall due to the physics explained in my other snowboarding post. When you are ready to attempt the 360, you have to figure out how to convert your linear momentum into angular momentum to complete a full rotation. In order to do so, you have to wind up your arms in the opposite direction of your planned rotation (about 75 degrees), and at the top of the jump swing them into the direction you plan on spinning. To help start the rotation, it is also recommended to turn your snowboard slightly in the direction you are planning on spinning right before taking off. Although it may be frightening to turn your back on the landing for a second, if you hesitate, you might not get enough rotational momentum and have a slow angular velocity, resulting in an incomplete rotation which means a pretty nasty fall. 

Once in the air, it is hard to notice anything as your angular momentum rotates your body, but the hardest part of the process is the landing. In order to land safely, it is necessary to convert the angular momentum back into linear momentum. Unfortunately, the ground will do this for you, but it most likely means that you will fall as well. Once you feel yourself about 3/4 of the way through the rotation, it is important to try to bring your arms back to in front of you. Also, attempt to kick your back foot opposite of the direction of the spin. Obviously it is impossible to completely take away the angular momentum while in the air, but the goal is to have as little angular momentum when you make contact with the ground. This also explains why it is sometimes easier to land a 360 on a larger jump because it requires a slower spin and therefore a lower angular momentum that can be stopped easier.

Similarly, a backflip is relatively simple (although it is extremely scary and you REALLY need to commit), but you still need to worry about stopping angular momentum. The first couple of times I tried a backflip, I landed well except my angular momentum was still very high and I would fall straight back immediately, hitting my head. Once I realized my problem, I aimed for more airtime and a slower rotation, and was able to stick the landing. 

So next time you are trying these tricks, or more likely watching the Olympics or X Games, pay attention to the awful effects of over-rotation due to the inability to stop angular momentum when trying to land.