Wednesday, 5 November 2014

Formula connecting Force and Power


Is there such formula? There probably is of course, but i would like a very concise description of how to derive it, in order to better understand myself. Thank you in advance.




Answer



Yes there is, first consider the original power formula


$P = w/t$


Now we know that work is equal to force.displacement (both vectors)


$P = (F.D)/t$


$P = F.(D/t)$


Displacement over time is velocity, so


$P = F.V$


Hence power can be stated as a dot product of the vectors force and velocity


Expanding the dot product



$P = FV\cos\theta$


Where $\theta$ is the angle between force and velocity, $F$ is magnitude of force, $V$ is magnitude of velocity.


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