So if i have a marble in a glass tube and i rotate the tube around in a circle . and the marble is at a distance r from the center of rotation . is the reason the marble goes towards the outside of the tube because when the glass tube starts to rotate the marble wants to go tangent to the circle so it is allowed to go further back in the tube when it rotates. and the end of the glass tube keeps it their . Is this what gives rise to the fictitious force .