Ok so I am an A2 physics student, and for one of my pieces of coursework I conducted a practical investigation, my topic being the factors affecting the period and swing of a bifilar pendulum.
The only useful information I was able to find on the topic was here: http://voyager.egglescliffe.org.uk/physics/gravitation/bifilar/bif.html
What I need to do is explain simply why increasing d in the diagram below, the distance between the threads on support A, while keeping d on bar B the same, will increase the period.
In the link I posted above, Faysal Riaz seems to explain this in this section:
"Therefore the restoring Couple, CR, which acts towards the equilibrium position so negative, is given by: CR = (-Mgθd2)/4y Applying Newton’s Second Law for the rotational motion of the rod, which is of constant mass: (Id2θ)/dt2= (-Mgθd2)/4y ∴(d2θ)/dt2= (-Mgθd2)/4Iy"
The problem is, I have no clue what this means. Can anyone simplify this so I could understand it better, or explain why decreasing d in the way I described above, increases the period in a few lines of basic mechanics if that's possible?