"An Introduction to the Physics of Sports" by Dr Vassilios M SpathopoulosThe Discus Paradox

An excerpt from the book: "An Introduction to the Physics of Sports" by Dr Vassilios M Spathopoulos.

There are some sports in which wind can assist a performance in ways that may have not occurred to us. Imagine that on quite a windy day you are about to take part in the discus throwing event. The games official gives you the choice. Will you throw into the wind or in the opposite direction?

Most people would think that throwing into the wind would cause a greater deceleration and thus produce a smaller range. Although it may defy common sense though, this actually is the right tactic to follow. Simulations have shown that the discus, if thrown correctly, can travel for up to 5-6m further if it is thrown against the wind.

How can this be the case? The answer is provided if we think of both aerodynamic forces acting on the discus. Apart from the drag, which increases due to the wind presence and so has a negative impact on the performance, there is also lift which will also increase in value due to the increased relative speed. Lift is the force that keeps the discus in the air so, the more it increases, the longer the flight.

By throwing the discus at the right angle the athlete can take advantage of this, thus overcoming the negative effect of drag. So apart from strength, discus throwing also requires quick thinking. On the other hand, it seems strange that strict wind limits have been imposed for events such as the 100m but not for others such as discus throwing where the effect is possibly greater.

athletics discus trowerAbout the Author

Dr Vassilios McInnes Spathopoulos has a PhD in Aerospace and Electronic Engineering from the University of Glasgow (UK). He has also completed a MSc course in Flight Dynamics at Cranfield University (UK). He currently teaches at the Department of Aircraft Technology, at the Technological Education Institute (TEI) of Chalkis, Greece. See more

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