Finding the speed in 3D motion

Question

Hi

 

I have been given the position vector of a particle, and have then differentiated this to get the velocity vector for the patricle. I have now been asked to find the speed, but am not sure how to do this. I have a feeling that it is really simple and I am just missing something obvious, but at any rate any help would be appreciated, thanks.

Answer 1

speed is the magnitude of vector, so speed = sqrt(vx^2+vy^2+vz^2) where vx, vy and vz are components of your vector in xyz coordinate system