A small 175-g ball on the end of a light string is revolving uniformly on a frictionless surface in a horizontal circle of diameter 1.0 m. The ball makes 2.0 revolutions every 1.0 s. What are the magnitude and direction of the acceleration of the ball?
The acceleration is directed toward the center of the circle.
To answer the questions that are asked, we don't need to know the mass of the ball that's revolving. We'd only need to know it if we were asked to find the centripetal force ... the force on the ball that keeps it on the circular path, i.e. the tension in the string.