1. The problem statement, all variables and given/known data A heavy ball swings on a string in a circular arc of radius 2 m. The two highest points of the ball’s trajec- tory are Q and Q′; at these points the string is ±28◦ from the vertical. Point P is the lowest point of the ball’s trajectory where the string hangs vertically down. The acceleration of gravity is 9.8 m/s2. What is the magnitude of the ball’s acceler- ation at the point Q? Answer in units of m/s2. 3. The attempt at a solution Wouldn't the acceleration at Q be 0 because there is no velocity at that point.