Solving Multiple Tracking Homework Equations for Answer

[AirForceOne]

Homework Statement

Homework Equations

The Attempt at a Solution

But the correct answer is 1227 ft/s^2.

Thanks.

 

[SteamKing]

Check your units for r2.

 

[AirForceOne]

Thank you. I was able to find part a) and r1. However, I was unable to find r^.. in part b). This is what I have so far:

I don't know how to integrate the acceleration vector to velocity vector it seems.