An astronaut is being tested in a centrifuge. The centrifuge has a radius of 8.5 m and in starting, rotates according to theta= .21t^2, where t in seconds give theta in radians. When t=5.0 s, what are the astronaut's angular velocity? I did .21(5.0)^2 / 5, to get angular velocity, but it was wrong. Can someone steer me in the right direction?