The relay switch consists of an electromagnet E and an armature AB (slender bar) of mass M which is pinned at A and lies in the vertical plane. When the current is turned off, the armature is held open against the smooth stop at B by the spring CD, which exerts an upward vertical force F_s on the armature at C. When the current is turned on, the electromagnet attracts the armature at E with a vertical force F. Determine the initial angular acceleration of the armature when the contact BF begins to close.

Transcribed Image Text:

Given: M = 20 gm F = 0.8 N Fs = 0.85 N a = 20 mm b = 30 mm C = 10 mm A D