1. The problem statement, all variables and given/known data A model airplane is controlled to fly in a horizontal circle of radius 24 metres with a constant speed of 20ms-1. An observer beneath the plane notices that the plane is flying anticlockwise. Find the magnitude of the change in velocity of the plane after: a- a full revolution b- a quarter of a revolution c- a half revolution 2. Relevant equations I have no idea on any equations. We haven't started the study of circular motion yet. 3. The attempt at a solution I really don't know where to start here. I guessed that the change in velocity after a full revolution would be 0 and that was correct (displacement =0) but im not sure on the other ones (B and C). They seem like random answers. Any ideas??