(source: google search) Artistic swimming, or synchronized swimming, is a water sport that combines elements of gymnastics, ballet, and swimming. Artistic swimmers usually perform routines either as solos, duets, teams, or combinations. These routines are made up of four main components: arm work, boosts, lifts and figures. Figures are the parts of routines where synchronized swimmers hold their breaths for a long period of time while they stick their legs out of the water and make elegant movements. In figures, the most basic position is a "vertical" where the swimmer is in a straight-line upside down in the water. (source: Journal of Student Research - Devin Johnson & Benjamin Simonds) As you can see in Figure 1, the higher a swimmer can get their body out of the water, the more points they can attain. The free body diagram shows that while the force of gravity is directed downwards, the force of buoyancy and water is directed upwards. It is also important to note the the force from air in the lungs can also be considered as an upward force since it decreases the swimmer's overall density. We use the technique called "sculling" to support ourselves on the water. This is also how the upward force of water is created. (source: theswimmingexpert.com) Sculling is the back and forth movement of the hands in the water so that the hands are pressing against the water at all times. Due to Newton's third law of motion, when the hands push against the water, the water pushes the swimmer in the opposite direction, which lifts the swimmer. As the motion changes from an inward to an outward sweep, the body also moves back and forth, following the direction of the force exerted on the body by the water. In a vertical position, since rising further out the water means reducing the buoyant force, the swimmer must scull harder to counter their weight. One of the highlights in team or combination routines is lifts. One person is thrown out of the water high into the air, and it is judged by execution and height. It is normal to have the lightest person on the team be lifted out of the air, and this can be explained by the concept of work and energy. (source: swimoutlet.com) Assume that the team is lifting a person with a larger mass M and a smaller mass m to the same height. The jumping person initially has no energy. At the maximum height, the jumper has both gravitational potential energy and kinetic energy. Since both types of energy involve mass in their equation (GPE = mgh, KE = 0.5mv^2), the jumper with a larger mass has more final energy. This means that the amount of work required to lift a person with mass M is larger. The force exerted on the jumper comes from the rest of the teammates. They stack themselves into a tower-like position to assist the jumper. Since "Work = Force * distance", and the distance the teammates move is the same for every lift (up until the surface of the water), the teammates have to exert more force to increase work done. However, this way, the teammates would have to use more of their chemical energy. Since lifts are normally located at the beginning of the routine, it is integral to preserve as much chemical energy as you can. This explains why the choreographers let the lightest person be the jumper in lifts. One of the more advanced techniques is a continuous spin. This is when the swimmers have to complete one or two 360-degree turns in a vertical position. (source: swimoutlet.com)
When we start the spin, our body is in a vertical position, with our arms at the side and bent 90 degrees at the elbows. The arms move in and out on a horizontal plane. We start spinning slowly, and when we have turned 180 degrees, we shoot our arms straight down towards the pool and spin the rest with a faster speed. We can relate the conservation of angular momentum to this situation. Since no external torque is acting on the swimmer, angular momentum is conserved. When the swimmer has her hands to the sides, the rotational inertia is larger since the mass is more distributed throughout the body (larger radius). This results in a slower angular velocity. As the arms shoots down, however, the rotational inertia decreases (smaller radius) and the angular velocity of the spin increases. However, it is important to note that the water resistance eventually slows down the spin as it interferes with the tangential velocity of the spin. It was very interesting to think about the physics behind a sport that I've been doing for a long time. Though I was taught to execute a technique in certain ways, I have never been taught of why I had to use those specific ways. I learned a lot of new things as I reasoned through certain techniques of synchronized swimming :)
0 Comments
|
Jenna Kimformer synchronized swimmer |