Motion
When we look at the physics of snowboarding, we first look to the Principles of Motion. Under motion, there are three major subsections...
- Newtons Laws
- One Dimensional Kinematics
- Two Dimensional Kinematics/ Rotational Kinematics
- Newton's 1st law states that an object will move with a constant velocity unless acted upon. This means that a object that is standing still will stay in place unless a force pushes on it. The concept of Inertia is the tendancy that and object stays at a constant velocity.
This applies to snowboarding when a snowboarder drops into the half pipe. He accelerates until he reaches the bottom and his inertia carries him to the opposite side of the half pipe so that he can do his trick.
This video gives a first person perspective of a half pipe which is a major area where newtons first law is applied.
2. Newton's 2nd law states that accelleration is produced when a force acts on a mass. This means that the greater the mass of the object, the more force needed to accelerate the object. If force is put on an object, it will accelerate in the opposite direction that the force is being put on.
Newtons second law applies to snowboarding when a snowboarder leans his body and the snowboard turns in the oppostie direction.
3. Newton's 3rd law states that for every action there is an equal and opposite reaction. All forces are an interaction between two objects and whenever two things interact, there is a action and reaction force. An action and reaction forces act on each other in opposite directions.
Newtons third law can be shown in many different ways. Newton’s Third Law of Motion is seen whenever a rider crashes into another object, whether it be another rider or a tree on the slope. If one person crashes into someone who is not moving, it may seem like the first rider delivered all the force to the stopped rider, but according to Newton’s Third Law, the still rider exerted the same amount of force on the moving rider, even though he wasn’t even moving. Of course, a more common accident would be a rider losing control mid-air off a jump and landing badly. In this case too, the rider is actually pushing down on the mountain, and the mountain is pushing back on the rider with the same force! Newton’s Second Law of Motion comes into play here as well. This law states that the force exerted on an object is equal to the product of that object’s mass times its acceleration, with the acceleration being in the same direction as the force. Even though two boarders colliding will exert the same amount of force on each other, the smaller rider will feel it more because the mass of the other rider is larger.
Next up is one dimensional kinematics
One dimensional kinematics is inertia, friction, and acceleration. Inertia is the concept that a body in motion tends to remain in motion, and a body at rest tends to remain at rest. When a snowboarder is at the top of a mountain, he is at rest and not moving due to the friction of his board against the snow. His board is perpendicular to the line down the mountain, with its back edge dug into the snow as to prevent moving. Even though the rider isn't using kinetic energy at that moment, his gravitational potential energy is very high because he is at the top of a mountain. He will stay at rest until the friction between the snow and his board is lessened to the point where he can cruise down the mountain. With the right incline of the mountain and position of his board, the rider will begin to accelerate down the mountain. Now although the snowboarder is accelerating as he leaves the top of the mountain, he also experiences friction all the way down the mountain. The rider experiences air resistance along with resistance from his board against the snow. However, snowboards are designed to minimize friction, and air resistance doesn’t play that big of a role in keeping him from getting to the bottom of the slope.
By turning slightly when going down a mountain, or carving, a rider can oppose his momentum and gain control. Carving is important because it allows a rider to glide around the mountain and maintain in control. The harder a rider carves, the more his speed is reduced.
Two dimensional kinematics
This is the exiting part for most spectators: Jumps and tricks
When a rider is about to go off a jump and attempt a crazy trick like you see in the X games, he has to create momentum in the direction he wants to spin in. Once this momentum is created and the snowboarder is spinning in the air, rotational inertia is exhibited, which states that a body that’s rotating tends to stay rotating, and a body at rest tends to stay at rest. The next step in the process is even more difficult: landing. In order to stick the landing on a jump, a snowboarder has to balance his weight over the center of gravity of the board so that he does not fall forwards, backwards, or any other way while landing. When you see a rider crash off a jump, often times it is a result of a misjudged spin or jump. If a spin is slightly over or under rotated, it can lead to a major wipeout, like shown below.
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