where a r = d e f ( d 2 r d t 2 ) r is the apparent acceleration in the rotating reference frame, the term − − Ω Ω × × ( Ω Ω × × r ) represents centrifugal acceleration, and the term − − 2 Ω Ω × × v r is the Coriolis acceleration. The last term, − − d Ω Ω d t × × r , is the Euler acceleration and is zero in uniformly rotating frames.