You mean position, not velocity. As you say, the acceleration vector, at any time, is <0, -cos(t), and you are given that the position vector is <2t, cos(t)>. At t= 2, those are <0, -cos(2)> and <4, cos(2)>. I can see no good reason to compare and .For the part of the problem where it asks to explain what the relationship between the accel. and pos. at t=2, I don't if I should compare the the accel. vector with the veloc. vector or compare the net accel. and net veloc.
Help, please. I know it's easy. I just don't know what they're asking for.