If you have a rod oscillating back and forth by a frictionless pivot point near the end of one side of the rod and the only external force is gravity, how would the magnitude and direction of the force of/on that pivot point be calculated? How does it change with the oscillations? I am having difficulty with this since torque would be ignored at that point and gravity is always pushing directly downward. I'm thinking the way to figure it out would be calculating the direction and acceleration vectors caused by the oscillations and include those forces caused by the oscillations in addition to the gravitational acceleration, but I'm not 100% sure about this one? I couldn't find a problem that looked at this aspect of oscillations anywhere in any of my physics books, so any help would be greatly appreciated.