Figuring Out Displacement Vector Direction

[LeakyFrog]

There is an attached image I couldn't figure out how to make it in the post.

The attempt at a solution
a)
So I know that the direction of the velocity vector will be in the direction on the displacement vector from P to Q:

2i+5j+3k

I also know that the magnitude of the velocity vector is 5cm/sec.

My thought on this is that we find the unit vector in the direction of the displacement and then multiply it by 5. So we get:

v = 5(2/sqrt(38)i+5/sqrt(38)j+3/sqrt(38)k)

Is this thinking correct?

 

[lanedance]

for a) yes, now for b)think about pramterising the line along which the particle moves in terms of time