The errors are not simply due to centrifugal force. The inertia of the pendulous vanes also plays an important part. This subject is too complex to explain in a single post here, but if you follow the attached link you will find an explanation of how these instruments work.
Once you have a good mental picture of how they work, you should be able to think through what happens during a full 360 degree turn.
Having said all of that, most students simply memorize the questions and answers when preparing for the ATPL exams.
www.TheAirlinePilots.com :: View topic - Air Driven Artificial Horizon