An inertial observer is one which is unacclerated (i. e. a=0 )`. A non inertial observer is an accelerated onserver. On this basis, we find that
(a) a child revoving in a giant wheel is a non-inertial observer.
(b) a driver with a constant speed is an inertial onserver.
(c ) at taken off, aeroplane has an acceleration. Therefore the pilot is a non-inertial onserver.
(d) a cyclist negotiating a sharp turn has an acceleration. Therfore he is a non-inertial onserver.
(e) the guard of the train is a non-inertial onserver, as the train in this case has retardation.