1. A coin placed on a 12" record will revolve with the record when it is brought up to a speed of 33.33 rpm. Provided the coin is not more than 4" from the axis... 2. a) What is the coefficient of static friction between the coin and the record? 3. I have calculated the velocity of the coin to be 27.92 in/s and the radial acceleration to be 194.92 in/s^2. Don't I need to calculate the tangential acceleration now to calculate the total acceleration? How do I calculate the tangential acceleration? I know the formula for ta is at = dv/dt.