고체역학 (Gere) — Axially Loaded Members: Problem 2.2-12

2.2-12 A small lab scale has a rigid L-shaped frame $ABC$ consisting of a horizontal arm $AB$ (length $b = 30\text{ cm}$) and a vertical arm $BC$ (length $c = 20\text{ cm}$) pivoted at point $B$. The pivot is attached to the outer frame $BCD$ that stands on a laboratory bench. The position of the pointer at $C$ is controlled by two parallel springs, each having a spring constant $k = 3650\text{ N/m}$, that are attached to a threaded rod. The pitch of the threads is $p = 1.5\text{ mm}$. If the weight is $65\text{ N}$, how many revolutions of the nut are required to bring the pointer back to the mark?