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...
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...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
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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.
Oatis C. (2009) Kinesiology: The Mechanics & Pathomechanics of Human Movement (Second ed.). Glenside, Pennsylvania: Lippincott Williams & Wilkins.
Newtons second law can be indentified more easily using the equation F=ma. This is an equation that is very familiar to those of us that wish to do well in any physics class! This equation tells us many things. First it tells us the net force that is being exerted on an object, but it also tells us the acceleration of that object as well as its mass. The force on an object is measured in Newtons (I wonder where they got that from). One Newton is equal to one (kg)(m)/s^2. For example, if superman pushes on a 10,000kg truck and it is moving at a rate of 2m/s^2, then the force that superman is exerting on the truck is 20,000N. For those of us that wish to move on in the field of physics, Newtons second law (F=ma) will forever haunt us!
Anderson, D. I., & Sidaway, B. (2013) Kicking biomechanics: Importance of balance. Lower Extremity Review Magazine.
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Dr. Kenneth Cooper set up the scientific purpose for running long distance in 1968 by publishi...
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Dapena, Jesus, and Alexander P. Willmott. “Scientific Services Project: (USA Track & Field),HIGH JUMP #23 (Men) Research Report.” “Diss. Indiana University, 2002.” Kirkpatrick, Larry D., and Gerald F. Wheeler. Fourth Edition Physics A World View. Fort Worth: Harcourt College Publishers, 2001.