1. The problem statement, all variables and given/known data A particle moves so that its position vector r at the time t is given by [tex]r=s(\cos \omega t \theta+\sin \omega t j)[/tex] with s and omega as constants. (j is meant to be a vector here) (1)Show that the acceleration of the particle is [tex]-\omega r^2 [/tex]. (2) Show that the acceleration of the particle is perpendicular to its velocity. 2. Relevant equations 3. The attempt at a solution (1) To find the acceleration vector, i guess i will need to differentiate the position vector twice. But i am not sure how to differentiate that. r=s cos omega t theta + s sin omega t j i don see any i vectors here ?