## Work

W = Fd

Great force exerted with **no distance** moved means **no
work** is done!

Units?Force in Newtonsdistance in meters

1 N-m = 1 J = 1 joule

Actually, we can say "Work = Force x distance" only when the Force and the distance moved

are in the same direction.If the force and the displacement do not lie along the same direction, then we must take the component of the force

parallelto the displacement and multiply that by the displacement. It is only the component of the forceparallelto the displacement that contributes to the work done.This means the general form of the definition of work is

W = F d cos Another way of describing this is called the "dot product" or the "scalar product",

Where we are using the mathematical notation of

AandBare vectors and S is a scalar. This is called the "scalar product of two vectors" or the "dot product" since it is indicated by a dot.where is the

angle betweenvectors and .

ToCPowerReturn to ToC, Work and Energy(c) 2002, Doug Davis; all rights reserved