Is there a centripetal force with a pendulum? My view is that mg acts on the mass (for angles lower than 90) with two components. One that is parrallel to the string and another that is perpendicualr to it. Since the center of the pendulum mechanism stays still, by action reaction this component is canceled out on the mass. For a time that goes to zero the mass moves in the direction that was perpendicular to the string. But since the string moves along with the mass, the direction of the mass (which is perpendicular to the string) changes constantly and the result is a circular motion. Is this perception correct or not?