The Physics of Efficient Running Essay -- physics run running

Running is a natural form of human locomotion. To many, running is an essential aspect of most sports and is also a simple way that requires little to get exercise anywhere. But because many people have adapted to improper forms of running over time, numerous physical injuries are the results. With the help of understanding the physics behind running, people can learn to run in such a way that expends less energy from the body. Keeping physics in mind may also lead to less injuries and effortless running. Remember, physics can be very helpful when running! External Forces When Running According to mechanical physics, a force is an effect that may cause a body to accelerate. Also as stated in Isaac Newton’s second law of motion, force is a vector quantity (has magnitude and direction) that is proportional to the product of the mass of a body and its acceleration. F = ma : where F is force; m is the mass of the body; and a is the acceleration due to that particular force When running, there are four important external forces that definitely affect the kinetics of running: drag force, gravity, normal force, and friction. Drag Force Due to the interaction with air on Earth, runners experience a resistive force against the airflow. This is called the drag force, or air resistance. The equation for this drag force is given as : Drag Force = 1/2pvvAD where p is the density of the fluid (in runner’s case: air); v is the velocity of the runner; A is the cross-sectional area perpendicular to the runner’s velocity; and D is the dimensionless quantity called the drag coefficient. The drag force is always working against the forward motion of a runner, trying to move them in the negative horizon... ...energy. -Second, hip rotation also helps the runner to have a more natural and smoother run and again reduces the energy required to move the runner’s center of mass. -Finally, the pelvic rotation decreases the impact at contact with the running path felt by the runner. Bibliography Dreyer, Danny and Katherine Dreyer. ChiRunning: A Revolutionary Approach to Effortless, Injury-Free Running. Simon & Schuster. New York, NY. 2004 Dumont, Aaron and Chris Waltham. â€Å"Walking.† Physics Teacher. Sept. 1997. Vol. 35 Issue 6, p. 372. Inman, Verne T., Henry J. Ralston, and Frank Todd. Human Walking. Williams & Wilkins. Baltimore, MD. 1981 Watkins, James. An Introduction to Mechanics of Human Movement. MTP Press Limited. Lancaster, England. 1983. Zatsiorsky, Vladimir M. Kinetics of Human Motion. Sheridan Books. Champaign, IL. 2002.