January 10, 2011

Science Class - by Curt Tomasevicz

As the second half of the World Cup season begins, I thought I would use this blog to educate and explain some of the details of bobsledding that most people (especially corn farmers in Nebraska) never consider. Just like farmers use a variety of sciences to increase their yields, bobsledders incorporate science every day in order to increase their speeds and clock faster times down the track.

Each bobsled track in the world is made up of anywhere between 14 and 20 curves. Each one of these curves is different. Looking at a track like a typical road map, you may notice that each curve has a specific radius as well as length. But in addition to this, you must remember that the track is also descending down a mountain, so each curve also has a drop in elevation. Therefore geometry and even trigonometry play a part in determining the fastest route through the curves. (Keep in mind that the shortest route is not always the fastest route in bobsled. Even though the shortest line through a curve is a low line, often times it is necessary to gain height in a curve in order to use gravity to accelerate out of the curve.)

{The American team pushes and loads into the sled during practice in Park City, UT.}

Chemistry is also a vital science used to be successful in bobsledding. Temperatures are measured to help aid competitors in choosing the best equipment. For example, if the ice temperature is well below freezing, the ice is much harder than ice that is just below the freezing temperature of water. Hard ice means that thinner runners on the sled must be used to dig into the ice to have control when driving. Fatter runners on the sled will simply glide on the surface and not provide much control. However, the fatter runners, because they skim the surface, create less friction and can prove to be a faster choice. In addition to the width of the runners, the metallurgic chemical makeup of the runners also plays a part. The FIBT (international governing body of bobsled) issues a standard chemical runner steel, but subtle differences are almost impossible to detect and for some unexplainable reason can aid or hinder the sled’s velocity.

{Centripetal force pushes the crew of the “Night Train” high on a curve as they travel over 90 mph.}

Perhaps the most common science used in bobsledding is physics. Mass is one variable that can be adjusted to affect a few different things. As a bobsled is travelling down a track, more mass equals more acceleration. There is, of course, a weight limit for the sled (with athletes) traveling down the track regulated by the FIBT (630 kg). But a heavy sled is more difficult to push fast at the start. So a team would prefer to push a light empty sled (also limited to a minimum of 210 kg in 4-man). Therefore a team must find a balance of a light empty sled to push and a heavy sled in which to ride down the track. Physics also plays a part in determining the energy a sled has as it exits a curve and accelerates to the next curve. Centripetal force can exert up to 5 G’s of force (five times that of gravity) on a sled as it passes through tight curves at high speeds.

Just like chemistry and biology play a vital role in producing maximum corn yields, bobsledders must also rely on science to succeed. Going to high school in central Nebraska, I certainly wouldn’t have thought I would need to use Mr. Lyon’s physics lessons on friction to help me strive for the Olympics!

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