Originally Posted by

**lauramorrison93** I am still obviously not fully understanding this and need more of an explanation.

What I have understood so far is that r is a vector with coordinates (x(t),y(t),z(t)). Where x(t)=t, y(t)=t^{2} and z(t)=t^{3}.

In order to find the rate of change of r I must find the derivatives x'(t), y'(t) and z'(t) which are 1, 2t and 3t^{2}, respectively. I also know you can write the coordinates in terms of unit vectors: r= t(**i**)+t^{2}(**j**)+t^{3}(**k**). Is this all correct? What happens to the unit vectors if that is the case?