Problem 3. Find the position vectors r(t) of a particle with acceleration function a(t) = (sin(t), cos(t), 7t), initial velocity v(0) = (0, 0, 71), and ini tial position vector r(0) : (0,1, 4>. Problem 7. True of False? Please motivate your answers. (a) Assume a particle has trajectory r(t), velocity v(t), and acceleration a(t). Then d E (rm >