Why does an object on a rotating disc fly off the disc as the speed of rotation is increased? To accelerate, the object must experience a net force in the direction of acceleration -- in this case, away from the disc, perpendicular to the object's velocity vector. But what is this force? When the speed of the disc is small, and the object remains stationary relative to the disc, it still needs an inwards force in order for it to be accelerating relative to me, right? Although relative to the disc, it doesn't feel any forces? Anyway, as the speed of rotation increases, so does the net inwards force on the disc and the net inwards force on the object on the disc (Fnet = v^2*m/r). Why shouldn't the object just remain in position, then?