grrr, my physics text is confuzzling!

 

it says w=fd

 

it says it is a scalar, and it also says w=fdcosx

 

f and d are vectors so, you can't just multiply them. which one is a magnitude or is it both? it looks like it is trying to get a projection of one vector on the other. that would make sense, but it said it was a scalar. is it a dot product? that would give a scalar.

first, I thought that two vectors multiplied give a scalar value.

 

And whats with this 'dot product', I heard my friend who's in advanced physics saying how regular multiplication and dot multiplication is totally different...

"multiplying" vectors is meaningless.

 

you have a dot product which gives a scalar value, and a cross product which give a third vector which is perpendicular to the first two.

well I'm pretty sure in equations like w = fdcosx it's given that its dot multiply... or at least that'd make sense

lol...

 

w=f.d

where bold values are vectors and the period is a dot product. The dot product can be rewritten as follows

 

w=f*d*cos(x)

where f and d are the magnitudes of f and d and the value x is the angle between the two vectors. The * signifies scalar multiplication.

The dot product tells you the projection of one vector onto the other. So in this case it tells you how much of the force is in the same direction as the displacement.