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Science & Sports
How an Athlete Used Physics to
Break an Olympic World Record
Almost 50 years ago, the Olympic high jump was
changed forever on October 20 in Mexico City. Dick
Fosbury, a 21 year old civil engineer missed the opening
ceremony and spent the week following up to his
event driving around to see the pyramids, watch the
sunset, and reportedly sleeping in a van. During his
high school years, after being too unskilled for basketball
and too small for football, Fosbury tried his luck in
the high jump. His coaches encouraged him to use the
previously known scissors or straddle technique which
brought Fosbury little success in the sport. When he
wasn’t able to compete with the more experienced
players, he had decided to change his technique. Instead
of jumping facing towards the bar in the traditional
straddle method, he jumped with his back towards
the bar and was able to improve his record and gain
more than half a foot. In the 1968 Olympics, he won the
gold medal for the high jump and set an Olympic record
of 2.24 meters. By the next Olympic games almost all
of the high jumpers had adopted this new technique
known as the Fosbury Flop. How did he manage to do
this? The secret behind his technique lies in a concept
known as the Center of Mass. For every object, we can
locate the average position of all of its mass by considering
how the mass is spread around the object. The
center of mass of a rectangle of uniform density will be
the intersection of its two diagonals. In other words, the
center of mass will be located above the balancing
point of the object.
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Similarly, humans also have a center of mass.
When we stand up, the center of mass is
around the belly. However, when you lift your
hands in the air, the center of mass moves upwards
and continues to move based on the position
the body is in. The center of mass can
also exist in a place where there is no mass at
all, a strange concept to think about, but it’s the
average point where the mass exists. For example,
donuts and boomerang both have a
center of mass that is outside the object. In the
Fosbury Flop, the jumper runs fast to divert
their horizontal velocity into vertical velocity. As
the jumper’s body bends backwards over the
bar, the center of mass of the jumper remains
below the bar. With the old techniques, the
jumpers were required to apply enough force to
lift the center of mass above the bar at least by
a few inches in order to clear it. The genius behind
the Fosbury flop was that by putting in the
same amount of force, but raising the body
much higher than before, so high that even if
the jumper’s center of gravity isn’t able to go
any higher, the jumper’s arched body can. Fosbury
brought the sport to new heights through
his revolutionary idea and changed Olympic
history forever.