A thin rigid rod is rotating with a constant angular acceleration around an axis that passes perpendicularly through one of its ends. At one instant, the total acceleration vector (centripetal plus tangential) at the other end of the rod makes a 60 degree angle with respect to the rod and has a magnitude of 15 m/s^2. The rod has an angular speed of 2.3 rad/s at this instant. What is the rod's length and what will be the rod's angular speed after 2.0 seconds?