A centrifuge is used for training astronauts to withstand large accelerations. It consists of a chamber (in which the astronaut sits) that is fixed to the end of a long horizontal and rigid pole. The arrangement is rotated about an axis perpendicular to the pole’s free end. Such a centrifuge starts from rest and has an angular acceleration of 0.25 rad/s2. The chamber is 3.0 m from the axis of rotation. Through what angle has the device rotated when the centripetal acceleration experienced by an astronaut in the chamber is four times the acceleration due to the earth’s gravity? i know that the angle= tan^-1 (a/w) to calculate a is a=(ac^2+at^2)^(1/2) but from this point i don't know what to do .