Energy Transformations

Energy transformations occur around us every day. We see energy transformations with almost everything we encounter; from the plant converting radiant energy into chemical energy, an animal converting chemical energy to mechanical energy, and transformation of potential energy to kinetic energy. We take most of this for granted because it is so intertwined with our most common activities, but without energy transformations we would not be able to survive. We need energy to flow through our world so that organisms can trap some of that energy and use it for their living processes. If the sun were to burn out tomorrow it would not be long before all living things ceased to exist. When energy transformations occur it is usually a conversion of potential energy into kinetic energy. Potential energy is energy that is stored for later use and kinetic energy is the energy of movement and performing work. In fact, the definition of energy is the ability to do work. This also occurs during sporting events, where almost all aspects of sports involve energy changes. We will look at these changes and see how they are used by athletes to pull off some of the most spectacular sports plays in history!

Potential Energy

In looking at energy it is important to remember that it is not something that is used and then disappears. According to the law of conservation of energy; energy is not created or destroyed; it only changes form. This means that energy has to be stored for some time before it is used to do work. When energy is stored it is considered potential energy. Potential energy can come in many forms; chemical potential energy, gravitational potential energy, nuclear potential energy and elastic potential energy. All of these forms store energy that can be released at a later time and used to perform some form of work. Just as a car stores energy in a gas tank, other things can store energy in other ways. For example a plant takes in energy from the sun and makes carbohydrates that hold energy in chemical bonds. This process is called photosynthesis and this energy can be stored for a long time. When you burn a piece of paper you are releasing energy that a tree stored a long time ago. We also use the energy in plants in our bodies. When we eat a plant we are consuming potential energy. The energy stored in that plant is released as we digest the plants contents and it provides our cells with that energy. If we are watching a sporting event where does the energy come from that the players use to perform the actions that we love to watch? It comes from the potential energy in the food they eat. Have you ever heard of players eating a pre game meal that is high in carbohydrates? The coach is trying to give the players all of the energy that they can in order to allow them to perform at their best. We will now look at how this potential energy is converted into kinetic energy that allows athletes to make the spectacular plays that we associate with sports.

Kinetic Energy

Kinetic energy is the energy of motion; it cannot exist without first being in the form of potential energy. Potential energy is converted to kinetic energy in order to do work. As kinetic energy increases, potential energy decreases at the same rate. Think of a ball that is lifted to a height of 10 meters. When it is held in the air it has only gravitational potential energy. If the ball is dropped it will increase in speed until it hits the floor. That increase in speed is the result of potential energy being converted into kinetic energy, the closer to the floor the ball gets the more kinetic energy it has but at the same time it is losing potential energy. This is the relationship between potential and kinetic energy. If we look at sporting events we can see these same transformations occurring all of the time. If a player jumps from the floor they are increasing their potential energy by transforming chemical energy from the food they ate into mechanical energy when the muscle contracts. This mechanical energy is used as kinetic energy to lift the player from the ground. When the player reaches the maximum height that he can achieve they no longer have kinetic energy, for a brief millisecond they have only potential energy before they start back toward the ground. As they descend that potential energy is converted back to kinetic energy as they move back to the floor due to gravity. As you can see the player went through several energy transformations but energy only changed forms, it did not go away. This type of energy transformation occurs all of the time during any type of sporting event. Players use energy from their food to complete many of the moves that we see during a typical game. A player that can master these energy transformations can learn how to precisely convert from one form to another to make the perfect shot, run the perfect play, hit a home run or shoot a puck from center ice to win the game!

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