Position vector R of a particle moving x-y plane

[chris61986]

Hello, new to these forums! I'm working on my UPI homework, and I just want to verify if I'm doing something correctly. The problem:

The position vector r of a particle moving in the x - y plane given by r = (2t^3)i + (6-7t^4)j, where r is in meters and t is in seconds.
Calculate
r
v
a
when t = 2s

Now, I'm pretty sure I know how to do it, but I don't get a second chance once I turn the homework in! :)

So in the original equation, r is meters. So I'm thinking this is the displacement.
If this is the displacement, I just plug in 2 for t and solve.
Because that's the displacement, I can find a and v from the derivatives of the original function.

Is this correct?

 

[tms]

Sounds good. Just remember that $\vec r$ is a vector.