Tatuagem "A força necessária ..."

Esta tatuagem é de uma equação que representa algo do tipo:

A força necessária para empurrar uma bicicleta e seu ciclista através do ar e para superar o atrito da tracção.

Fonte: http://blogs.discovermagazine.com

Eis a explicação :)

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There is a well-known equation that gives the power required to push a bike and rider through the air and to overcome the friction of the drive train:

,

where  is in watts,  is Earth's gravity,  is ground speed (m/s),  is bike/rider mass in kg,  is the grade (m/m), and  is the rider's speed through the air (m/s).  is a lumped constant for all frictional losses (tires, bearings, chain), and is generally reported with a value of 0.0053.  is a lumped constant for aerodynamic drag and is generally reported with a value of 0.185 kg/m.^[17] If there is no wind,  and the result simplifies to:

,

which is proportional to the ground speed cubed in its leading term.

(...)

Fonte: http://en.wikipedia.org/wiki/Bicycle_performance