This doesn't exactly have to do with the title, but generally comes up in this sort of thing. I'm feeling pretty dense right now to not be able to understand what's going on.. but my text book isnt exactly helping.(adsbygoogle = window.adsbygoogle || []).push({});

lets say there is a function which relates a particles position, r, with respect to time, t: (w is representative of the period)

r=3cos(wt)i + 4cos(wt)j + 5sin(wt)k

its derivative should give you its velocity

v=-3wsin(wt)i - 4wsin(wt)j + 5wcos(wt)k

the magnitude of the velocity vector should give the speed of the particle

s= ?? (the book suggests the answer is s=5w)

How does one arrive at the magnitude of vector v?? I can do this in a case where we are looking at simple coefficients of i,j, and k... but with the trig in there, I'm getting sorta confused. If someone would post up a step-by-step, it would be much appreciated!

Thanks!! Sorry for asking such a simple question.. probably goes back to grade 10 math that I've just forgotten! lol

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# Homework Help: Vector Functions, Differentiation

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