# Effect of wind speed on running

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1. Oct 25, 2015

### Jank

Hi guys,

I'm an arts undergrad student with very little knowledge of the sort of physics I'm about to ask.

I was wondering if there is a calculation to work out the differentiation between running at a particular speed say 10mph against wind coming towards you at 15mph. As well as it being on flat & say the person being about 60kg and about 1.7 metres tall (average person).

Obviously if there was no wind against you, you would runner faster, and even faster with wind behind you.
Whats the calculation (in layman's terms) to work out the difference?

I've linked some articles below which I've read and tried to understand, I know its something to do with velocity, drag and inertia.

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http://jap.physiology.org/content/48/4/702
https://www.brunel.ac.uk/~spstnpl/Publications/WindAccuracy(Linthorne).pdf
http://rmseura.tkk.fi/rmlehti/1997/nro2/RakMek_30_2_1997_1.pdf
http://engineeringsport.co.uk/2011/05/04/the-loneliness-of-the-long-distance-physicist/

2. Oct 25, 2015

### Jank

Just wanted to add that I am a runner and the reason I started thinking about this was because I wondered if this website:

http://runsmartproject.com/calculator/

Has a legitimate way of calculating wind difference.

3. Oct 25, 2015

### DaveC49

From what I remember of drag on an object in fluid dynamics ( air is a fluid), the drag force is proportional to the velocity squared with a constant of proportionality which is related to the cross-sectional area and fluid density (but also has some 3D shape dependence because of laminar-turbulent flow effects). Look for calculations of terminal velocities of free falling objects for example. Without knowing how the calculation is actually performed on the web site it is difficult to judge how accurate it will be. It is unlikely that such calculations are likely to be absolutely accurate without calibration (to determine the constants of proportionality in the drag force for a given individual) but it is likely that they will be indicative. It would appear that Jack Daniels has tables, presumably of experimental measurements which are used in the calculator, but the website contains no reference to this data or discussion of the theoretical basis on which it is derived. It may be described in Jack Daniel's book, which is not referenced, but is presumably available. A case of insufficient information at this point on which to judge whether the approach is scientifically based and valid.