The physics behind Long Jumping and Hurdling In Track & Field

For nearly 7 years, Track and Field was part of my daily routine. While I mainly stuck to running, I was still given the opportunity to attempt other events such as pole vault. However, two of my favorite events to watch were always hurdles and long jump. Taking this course consequently piqued my interest in understanding the physics behind these events. 

In a hurdling event, many of the concepts we have learned can be applied. During this race, a person will run over a certain distance, jumping over hurdles in the process. Typically, this person’s body can be seen to be “tucked in” as they jump over the hurdles. This is a form most commonly used and seen. With beginners, it is a technique that is often taught very early on. In hurdling, it is most ideal to have a center of mass that is just above the hurdle so that the runner can reach the ground faster after clearing the obstacle. Therefore, the “tucked” position, which is better described as a lean, can be understood to help accomplish this. In addition, to be able to clear the jump, Newton’s second and third laws of motion must come into play. His second law, which states that the sum of the forces is equal to mass times acceleration (ΣF = ma), relates the mass of an object to the net force acting on said object. Taking this relationship into account, a person of a bigger mass must exert a greater force on the ground in order to effectively clear the hurdle. This also has to do with Newton’s third law, which simply states that for every action there is an equal and opposite reaction. Right before a jump, the forces acting on the runner in the Y-direction are that of gravity (FG) and the Normal force from the track (FN). To jump, the hurdler must exert a force on the track that will then equal a force exerted by the track on the runner. Conclusively, the more force exerted on the track by the runner, the easier it is for them to jump and clear the hurdle. Finally, one of the most obvious physics concepts observed during hurdling is that of projectile motion. On a day with minimal wind (and therefore air drag), the runner, while in the air during a jump, becomes influenced almost exclusively by the force of gravity. As a result, their horizontal velocity remains almost constant and their path taken is best described as a parabola. 

As expected, the same physics concepts are observed in a long-jumping event in which a person runs a given distance, gathering speed before jumping a seemingly parabolic path into a pit of sand. Other concepts, such as that of momentum which occurs right before the jump, can also be observed.

Sources: 

https://sites.google.com/site/thelongjumpproject/the-science-of-long-jumping

http://lsakelseyc1.weebly.com/newtons-law.html