1. The problem statement, all variables and given/known data Mary sits on the perimeter of a merry-go-round undergoing uniform circular motion. Matt stands on the ground 12 m from the centre of the merry-go-round. Matt observes Mary coming towards him at a speed of 1 m/s. What is Matt's speed from the point of view of Mary? (Ans: 2m/s) 2. Relevant equations 3. The attempt at a solution I made a sketch according to the given problem. A denotes Mary and B denotes Matt. Shouldn't the answer be 1 m/s? If Matt observes Mary coming towards him with 1m/s, then Mary should also observe Matt coming towards her with 1 m/s. I don't see why this is wrong. Any help is appreciated. Thanks!