Juan Miguel Echevarrìa and the physics behind the perfect long jump

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Juan Miguel Echevarría participating at the Stockholm 2018 IAAF Diamond League. Photo: Matthew Quine/IAAF Diamond League

Just a few inches further and he would have jumped out of the pit. In fact, there is quite a strong argument to suggest that in landing at 8.83m in the long jump at the Stockholm Diamond League on June 10th, Cuba’s Juan Miguel Echevarria actually cut his jump short as he approached the end of the sand.

This may have been a split-second, conscious decision; it may have been a sub-conscious decision by his brain recognising that he was plummeting towards a very uncomfortable landing. Either way – the jump could have been further – perhaps even over 9m.

But how does a 19-year-old, with a fairly average 100m PB of 11.52, defy the laws of physics in order to jump 50cm longer than a Routemaster double-decker London bus? Even with a tailwind – a mere 0.1m per second more than allowed under IAAF law – this is certainly an impressive feat.

Melvin Ramey PhD, who up until his death in June 2017, worked with USA Track and Field as a biochemist and engineer, explained in 2012 that in creating the physics of a perfect long jump, “the human body becomes a projectile”.

In order for the human body to reach the ideal trajectory required to almost clear a long jump sand pit, it must maximise its horizontal velocity (the speed gathered on the runway) and its vertical velocity (the speed at the point of takeoff), and combine these two factors with the perfect takeoff angle when leaving the long jump board.

Sounds easy, right? You run really quick, take off really quick, and jump at an angle that would allow you to jump high in to the air – which many people would assume would be exactly in the middle between 90° and 0°.

It isn’t quite that simple. Ramey determined that a 45° angle of takeoff was too steep; gravity acts on vertical velocity, so a take off of this height would simply result in the jumper being pulled back towards the sand. In fact, the ideal take off angle is between 18° and 22°, which allows the athlete to create a perfect combination of speed and height in the flight phase.

Once you’ve mastered the ideal combination of horizontal and vertical velocity, you then have to contend with external factors, such as wind or air drag. A following wind can give a jumper extra speed and height, potentially leading to a longer leap.

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Equally of course, a headwind can work against the forces created by the athlete, reducing their velocity and negatively impacting on the length of the jump. Air drag can also make a big difference to velocity; high-altitude regions such as the Alps tend to have thinner air, reducing the resistance applied to an athlete as they move.

There is no denying that Echevarria’s 8.83m jump took place in a venue with relatively thin air and a following windspeed of 2.1m per second, but it was still the furthest leap in the world since 1995.

He has since backed up this jump with an 8.66m in Ostrava on 13th June, which with a following windspeed of 1.0m, just so happens to be the longest legal jump in the world this year.

Inspired by an original article posted here.

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First published on: 21 June, 2018 4:13 pm

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