Monday is the start of the Nordic ski season! (That's cross country skiing for those of you who don't know) Skiing, particularly Nordic, has tons of potential for physics conversations. I'm going to focus particularly on poling.
To get the most out of poling while racing, its necessary to go the fastest while also using the least amount of energy. In order to achieve this it's important that the poles are planted as close to 45 degrees to the ground as possible. Physically, this makes total sense. Your sine and cosine components of force would then be equivalent. You would not be wasting energy pushing yourself vertically off the ground and you get the most forward push with every plant. Then, you use the least amount of energy for the amount of momentum you gain, since a stronger push gives you more velocity and momentum = mass*velocity. Momentum is crucial in skiing because more glide means that you can go farther and faster than the person next to you without getting totally exhausted too soon.