Understanding Velocity and Vector Calculus for Moving Objects

[Engels]

Homework Statement

An object moves according to this : r(t)= (1+t^2)i + (1-t)j + (t+t^3)k

How fast does it moves far from O(0,0) for t=1?

Is this velocity the same with the object's velocity?

The Attempt at a Solution

I can't understand the second part

 

[radou]

I can't seem to understand the second part either.

By the first one, do you mean, what its velocity is at t = 1, or what its position is? What is the relation between the two?

 

[Engels]

i mean the velocity for t=1 which is r'(1)= 2i-j+4k
The r(t) in my previous post is the position vector from the start (0,0)

is the any reason for not the r'(t) or r'(1) to be the objects velocity?