A simple pendulum of mass 15 kg with a period of 1.8 sec is displaced an angle of 10 degrees from the vertical. What would its acceleration be in the vertical (y) direction as it reachs the lowest point on its swing? ********** Ok, I understand that it is a simple pendulum, but how do I figure out the acceleration? Some help in the right direction would be helpful. I bet this is a simplistic problem, and I'm gonna hit myself in the head when I figure out what it is.