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TomLikesPhysics
r(t)=(2t, wt, 4t) in cylindric coordinates. How do I find v(t)?
I can't see how it is anything other than just differentiating wrt t
I think the problem is that the unit vectors in cylindric coordinates also vary with time so it is not just v(t)=(2,w,4)
so the directions here are\[\hat r,\hat\theta,\hat z\]I suppose, eh?
do you know the answer?
No, however I just computed v(t)=(2, 2t*w, 4) but I don´t know if is correct or not.
I also have no clue how I could ask wolfram alpha to check that.
I used this formula but I am not entirely sure if this formula fits that problem.
I have never seen that formula, so I can't verify it...
I thought this is a "simple" problem.^^
http://www.maths.ox.ac.uk/system/files/coursematerial/2012/1115/77/CylCoords.pdf that formula you have seems to be right, though I can't seem to see where they get the extra rho from
The extra rho comes from the derevative of the unit vector e in the direction of phi.
ahh, okay, I had to read that sheet a but closer to get it thanks!
No problem, you´re welcome.