# Math Help - Position vectors

1. ## Position vectors

I am having trouble solving this problem, can anyone help me out...please!

A particle traveling in a straight line is located at the point (1, -1, 2) and has speed 2 at time t=0. The particle moves toward the point (3, 0, 3) with constant acceleration 2i+j+k. Find its position vector r(t) at time t.

any help is greatly appreciated
thank you

2. It would be easier if you specified what part of the problem you found difficult. I'm going to assume it is the accelleration vector.

What if I tell you that

$\vec{a}(t)=\frac{d\vec{v}}{dt}=\frac{d^2\vec{p}}{d t^2}$ If you don't know, $\frac{d^2\vec{p}}{dt^2}$ is the second derivative of $\vec{p}(t)$.
Then, $\vec{p}(t)=p_1i+p_2j+p_3k \, \Rightarrow \, \vec{v}(t)=\frac{dp_1}{dt}i+\frac{dp_2}{dt}j+\frac {dp_3}{dt}k$

or something like that, and so on.

Was that understandable?