This Olympics marks the 40th anniversary of when Dick Fosbury changed the high jump. His angled-approach, backward jump was quickly dubbed the &#8220;Fosbury Flop.&#8221;</p><p>Previous to the 1968 Games in Mexico City, the common high jumping technique was the straddle style. An athlete would run toward the bar and jump face-down over the bar, throwing one leg over followed by the other.</p><p>From a science standpoint, this was a bad method, because it meant the center of mass had to clear the bar.</p><p>&#8220;Center of mass is almost the average part of the mass,&#8221; said UMKC physics professor Michael Kruger, who teaches a course called &#8220;The Physics of Sports.&#8221;</p><p>What is center of mass? Kruger said to imagine balancing a pencil on your finger. Where the pencil rests on your finger is the center of mass.</p><p>&#8220;Since we&#8217;re not pencils, we can move our center of mass,&#8221; Kruger said. &#8220;You can manipulate your center of mass. If you raise your arms up, you can raise your center of mass.&#8221;</p><p>Of course, in the high jump you want to lower your center of mass to get over the bar.</p><p>In the Fosbury Flop, the jumper arches his or her back above the bar. The head and shoulders pass over the bar first, and at one point the high jumper&#8217;s body appears to form a semicircle with the legs on the other side of the bar.</p><p>&#8220;What he was able to do with that high jump technique was to allow athletes to keep their body above their center of mass,&#8221; Kruger said.</p><p>In fact, while the high jumper&#8217;s body clears the bar, the body of mass doesn&#8217;t necessarily do that as well.</p><p>How can that be?</p><p>Kruger offers another example: where is the center of mass on a doughnut? Logic tells you it should be in the center, but there&#8217;s no mass at that point.</p><p>&#8220;The center of mass of an object doesn&#8217;t have to be where there is mass,&#8221; Kruger explained. &#8220;It can be where there is no mass.&#8221;</p><p>Kruger said in the old method, the center of mass often was near the belly button. The Fosbury Flop allows the center of mass to go under the bar. That&#8217;s why Fosbury&#8217;s gold-medal winning jump was 2 1/2 inches higher than the 1964 winner.</p><p>It was a scientific breakthrough. Not that he spent time doing calculations in his head.</p><p>&#8220;It was not by design at all,&#8221; Fosbury told the London newspaper <em>The Independent</em>. &#8220;It was just simply intuition. It was not based on science or analysis or thought or design. It was all by instinct. It happened one day at a competition. My mind was driving my body to work out the best way to get over the bar.&#8221;</p><p>And the rest was history.