Transverse-fluctuation calibration of a tensioned tether
= Transverse-fluctuation calibration of a tensioned tether
For a tether with extension $\ell$ and tensile load $F$, a small transverse coordinate costs $Fx^2/(2\ell)$. Equipartition gives $F=k_BT\ell/\langle x^2\rangle$ for one Cartesian transverse coordinate. Using the sum of two transverse variances changes the factor of two. Geometry and measurement filtering must match the calibration model.