Roller coasters are almost entirely driven by different forces of inertia, gravity, and centripetal. The physics of a roller coaster also involves work, energy, friction, inertia, and air resistance. A roller coaster usually begins with a mechanical device, such as a chain and motor, which exerts a force on the car trains to lift them to the top of the hill. At this point, gravity takes over and the duration of the ride undergoes energy transformation. This first hill of a roller coaster is normally the tallest. Once the cars are pulled to the top of the hill, they maintain gravitational potential energy. The first hill maintains the largest amount of potential energy. Gravitational potential energy is the energy an object possesses because of its position in a gravitational field. It is the amount of work an object will be able to do with the energy it builds from falling. The equation for potential energy is PE=mgh. “M” is for the mass, “g” is for the gravity constant of 9.81m/s2, and “h” is for height. This energy is proportional to the mass of the cars and the height of the hill. As the cars descend down the hill, the potential energy is exchanged for kinetic energy (Harris, 2007). Kinetic energy is the energy an object possesses due to its motion. It is the work needed to accelerate a body of mass from rest to a given velocity. Kinetic energy is gained when an object accelerates, and the body maintains this energy until its speed changes. The equation for kinetic energy is KE= ½ mv2, where “m” is the mass of the object and “v” is the velocity. As the roller coaster descends, it is accelerating, creating kinetic energy. The kinetic energy is the largest at the bottom of the first hill. The energy of the roller coaster cars will continue to change from potential to kinetic energy, and vice versa, as the cars ascend and descend the hills. Due to frictional losses, the total energy only decreases throughout the ride; therefore, the maximum hill the cars can climb gets smaller and smaller (Harris, 2007). The energy built up from the first hill has to be enough to take the cars to the end of the ride. This change in energy demonstrates the Law of Conservation of Energy. The Law of Conservation of Energy states that energy can change from one form to another, but cannot be created or destroyed. As the roller coaster changes from potential energy at the top of the hill to kinetic energy at the bottom, it is representing the Law of Conservation of Energy (Johnson, 2006). The cars are continuously losing and gaining height throughout the ride. Every height gain corresponds with the loss of speed as kinetic energy is transformed into potential energy. Every height loss corresponds with a gain of speed as potential energy is transformed into kinetic energy (Johnson, 2006). Energy throughout the ride is neither gained nor lost, but is simply transformed from potential to kinetic energy and vice versa. The work and energy relationship is demonstrated in a roller coaster ride. The work done by an external force is capable of changing the total amount of mechanical energy. The equation KEinitial + PEinitial + Wexternal = KEfinal + PEfinal explains the relationship. The amount of work done by external forces is equal to the amount of change in the total mechanical energy of the object. The left side of the equation includes the total mechanical energy for the initial state plus the work done by external forces. The right side of the equation includes the total mechanical energy for the final state of the object. The weight of the roller coaster is pulled down by gravity, meaning that the cars are falling. The two major types of roller coasters are steel and wood. The features in these wheel designs prevent the cars from flipping off the track. Wooden tracks tend to have less complex loops as steel tracks, because it is more inflexible than steel. Tubular steel tracks were introduced in the 1950s. The nylon or polyurethane wheels run along the top, bottom, and side of the tube. This secures the cars to the track while it travels through loops and twists. As the cars flip during loops, inertia keeps one in his seat. Inertia is the resistance of any object to any change in its state of motion. It is the tendency of an object to continue motion in a straight line at a constant linear velocity (Roller Coasters, 2013). This includes Newton’s First Law of Motion. Although gravity pulls us towards the earth, the acceleration force at the top of a loop is pulling upwards stronger than gravity is pulling downwards, thus counteracting gravity and allowing one to remain in the cart. A loop but also be elliptical rather than a circle, because the centripetal force would be too strong for both safety and comfort. Centripetal force is a force that acts on a body moving in a circular path and is directed toward the center around which the body is moving. When the roller coaster goes around a turn, the centripetal force pushes you against the outside of the car to help keep you in the car. Friction is a force that resists the relative motion or tendency to such motion of two bodies or substances in contact. Some of the energy in a coaster is changed into friction; therefore, each successive hill in a roller coaster is made smaller because factors such as friction slow down the roller coaster. Friction slows the roller coaster down by holding the car down. Less friction will increase a roller coaster’s velocity. When the cars of the roller coaster ascend hills, they have to fight off both friction and gravity to get to the top. Once the cars have reached the top of the hill, friction is overcome. At this point, the potential energy becomes kinetic and the speed of the cars increases until the bottom of the hill (Ratliff, 2011). Wind resistance and the rolling of wheels also use energy. The energy during a roller coaster ride is spread into different areas. A lot of the energy goes to the friction between the roller coaster and the track, which allows the roller coaster car to slow down. Additional energy is lost due to wind resistance and gravity. If gravity overcame the forward motion of the roller coaster cars as they climbed the hills, then the ride would never make it to the top of a hill. Energy is also lost in angular momentum from twists and turns. Ultimately in roller coasters, the energy will always be dispersed. It is nearly impossible to make a 100% efficient roller coaster, or else it would never end. Higher efficiency in the wheels and better streamlining have made a big difference in how long the system can retain energy, but it will never be perfect. Factors such as friction, air resistance, and the Law of Conservation of Energy make it impossible for perfect efficiency. Chandler, M. (2012, January 1). How Roller Coasters Work. Kidzworld. Retrieved, from http://www.kidzworld.com/article/4633-how-roller-coasters-work Harris, T. (2007, August 9). How Roller Coasters Work. HowStuffWorks. Retrieved, from http://science.howstuffworks.com/engineering/structural/roller-coaster.htm Johnson, T. (2006, July 11). First Hill on A Roller Coaster is the Biggest. University of Illinois. Retrieved, from http://van.physics.illinois.edu/qa/listing.php?id=31 Ratliff, D. (2011, June 6). What Causes Roller Coasters to Slow Down?. eHow. Retrieved from http://www.ehow.com/info_8549322_causes-roller-coasters-slow-down.html Unknown. (2013, August 13). Roller coasters. Why don’t I fall out when a roller coaster goes upside down? (Everyday Mysteries: Fun Science Facts from the Library of Congress). Retrieved, from http://www.loc.gov/rr/scitech/mysteries/rollercoaster.html |
What happens to the value of potential energy and kinetic energy as the coaster is moving throughout the entire coaster ride do not consider air resistance or friction?
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