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Physics vocabulary & figure skating
Just a thread of physics terms explained with fs examples.
Might add more in the future
Just a thread of physics terms explained with fs examples.
Might add more in the future
ENERGY
Kinetical energy (KE)
It's the energy due to a body's movement. We will devide it as translational KE and rotational KE.
However, for convenience, in my threads I refer to translational KE as KE alone, and to rotational KE as rotational energy.
Kinetical energy (KE)
It's the energy due to a body's movement. We will devide it as translational KE and rotational KE.
However, for convenience, in my threads I refer to translational KE as KE alone, and to rotational KE as rotational energy.
Translational KE (KE in threads)
It's due to translation and it's calculated as ½mv², being "m" the mass of the skater and "v" their velocity. Note that more speed means even more KE as "v" is squared.
Faster skaters will have more KE to then convert it to other kinds of energy.
It's due to translation and it's calculated as ½mv², being "m" the mass of the skater and "v" their velocity. Note that more speed means even more KE as "v" is squared.
Faster skaters will have more KE to then convert it to other kinds of energy.
Rotational KE (Rotational energy (RE) in threads)
It is due to the rotation along one axis (vertical axis in our case) and it's calculated as ½Iω², being "I" the momentum of inertia (shape/posture of the skater) and "ω" the angular velocity (rotational speed)
It is due to the rotation along one axis (vertical axis in our case) and it's calculated as ½Iω², being "I" the momentum of inertia (shape/posture of the skater) and "ω" the angular velocity (rotational speed)
From translational into rotational
This is the main feature in both spins and backward edge jumps. It's done through the footwork, starting from a curve that gets tighten until the they get to rotate along the vertical axis.
This is the main feature in both spins and backward edge jumps. It's done through the footwork, starting from a curve that gets tighten until the they get to rotate along the vertical axis.
Due to this process, the linear speed after the take off in edge jumps will be significantly lower, which makes these jumps (S and Lo) shorter on average than toe jumps.
This is especially remarkable on the Loop, where most of the rotational momentum comes from this process
This is especially remarkable on the Loop, where most of the rotational momentum comes from this process
Potential energy
It's the energy due to the height reached. It's calculated as mgh, where "m" is again the mass of the skater, "g" the gravity (9.81m/s²) and "h" the height.
It's the energy due to the height reached. It's calculated as mgh, where "m" is again the mass of the skater, "g" the gravity (9.81m/s²) and "h" the height.
Elastic energy
It's the energy storaged in anything similar to a spring, in our case muscles, especially leg muscles. However due to the variability in human body this is the most difficult one to model mathematically.
It's the energy storaged in anything similar to a spring, in our case muscles, especially leg muscles. However due to the variability in human body this is the most difficult one to model mathematically.
From elastic to potential and back
This is the process that allows skaters to jump. They first get into a low position that allows them to get elastic energy to then release it and gain height. Then the potential energy due to that height becomes elastic energy on the landing
This is the process that allows skaters to jump. They first get into a low position that allows them to get elastic energy to then release it and gain height. Then the potential energy due to that height becomes elastic energy on the landing
DYNAMIC
Newton's 1st Law:
An object in rest/linear motion stays at rest/linear motion unless an external force changes that.
Which means if you wanna change your speed or direction, you will need to apply a force. If that force disappears you will move on a straight line until
Newton's 1st Law:
An object in rest/linear motion stays at rest/linear motion unless an external force changes that.
Which means if you wanna change your speed or direction, you will need to apply a force. If that force disappears you will move on a straight line until
something stops you.
Wikipedia uses this gif to explain it. The rope is applying a force (tension) to the object that makes it turns (change of direction). When it breaks the object continues in the direction it had at that moment.
Wikipedia uses this gif to explain it. The rope is applying a force (tension) to the object that makes it turns (change of direction). When it breaks the object continues in the direction it had at that moment.
I, however, very much prefer this other example.
It's the same process, just change the rope breaking for the blade slipping
It's the same process, just change the rope breaking for the blade slipping
Newton's 2nd Law:
It basically states that a force is calculated as F=ma, being "m" the mass and "a" the acceleration.
It's everywhere and used for everything, which is cool, but also there isnt any particular simple situation to show this. So here this just because I love it
It basically states that a force is calculated as F=ma, being "m" the mass and "a" the acceleration.
It's everywhere and used for everything, which is cool, but also there isnt any particular simple situation to show this. So here this just because I love it
Newton's 3rd Law: Action-Reaction
The same force you apply to an object it will apply it back to you on opposite direction.
A perfect example of this is the take off, especially in toe jumps. The force that the skater exerts down against the ice is the same that propels them up
The same force you apply to an object it will apply it back to you on opposite direction.
A perfect example of this is the take off, especially in toe jumps. The force that the skater exerts down against the ice is the same that propels them up
Angular/rotational momentum
It can be defined as the amount of rotational movement an object has. It is calculated as L=Iω, which means that, in comparison with the rotational energy, the shape of the skater is now as important as their rotational speed
It can be defined as the amount of rotational movement an object has. It is calculated as L=Iω, which means that, in comparison with the rotational energy, the shape of the skater is now as important as their rotational speed
Conservation of rotational momentum
This is one of the main laws in fs physics. It states that the quantity L must be conserved if there isnt external forces. So if the shape of the skater changes, their rotational speed will change as well proportionally
This is one of the main laws in fs physics. It states that the quantity L must be conserved if there isnt external forces. So if the shape of the skater changes, their rotational speed will change as well proportionally
Example:
He is spining with a constant speed, the moment he close the free leg his shape changes decreasing his momentum of inertia (I), as he's taking part of the mass closer to the axis. So the rot speed increases. You can see this effect when he opens and close the free leg
He is spining with a constant speed, the moment he close the free leg his shape changes decreasing his momentum of inertia (I), as he's taking part of the mass closer to the axis. So the rot speed increases. You can see this effect when he opens and close the free leg
Important:
Rot. energy is not conserved while rot. momentum does. This means that, especially for jumps, it's more benefitial to go with high momentum than with high energy. A slower entry with better shape can make a jump easier to rotate than a faster one but with worse form
Rot. energy is not conserved while rot. momentum does. This means that, especially for jumps, it's more benefitial to go with high momentum than with high energy. A slower entry with better shape can make a jump easier to rotate than a faster one but with worse form
