1. The problem statement, all variables and given/known data A 68.8 g steel ball is attached to the end of a string. The ball is swung in a vertical circle 86 cm in diameter. (a) What is the minimum speed the ball must have at the top in order to complete the circle without falling? (b) If this speed is constant, what will be the tension in the string at the bottom? Draw a separate FBD for both parts. Show all work. Hint: minimum speed to complete the circle is the velocity needed to keep the ball from falling when the tension at the top is just zero 2. Relevant equations 3. The attempt at a solution We know mass...(68.6g or .0686kg) and we know the radius (86/2 is 43) I just dont know where to go from here??? for Part a) at the top of that circle....we know that mg (force of gravity is acting downwards) and centripetal force is also acting downwards but is this really a centripetal acceleration problem? A_c = V² / R we know what R (radius) is....but we need V (velocity)....and how do we figure out what A_c (centropetal acceleration) would be?? any hints here?