Wednesday, 12 August 2020
Forces on the fence at Chanonry Point
I was wondering about the physics of this fence post by the lighthouse on Chanonry point. I'm going to estimate som distances and assume the forces F2, F3, F4 and F5 are identical to simplify it. I'll call that idenical value F. Assuming the post is about 1 metre high and taking moments about the pivot, F1xsin50x1 = Fx1 + Fx0.75 + Fx0.5 + Fx0.25 which means F1= 3.26 x F. By this arrangement, the diagonal strand is not taking 4x the force, although there are 4 identical wires. The diagonal wire was also doubled up so each strand would only take half the force.