Bar ABC is attached to collars A and B that can move freely on the rods shown. The constant of the spring is k, and the spring is unstretched when θ = 0.
(a) Neglecting the mass of bar ABC, derive an equation in terms of θ, m, g, k, and l that is satisfied when bar ABC is in equilibrium.
(b) Determine the value of θ corresponding to equilibrium when m = 5 kg, k = 800 N/m, and l = 250 mm, and check that the equilibrium is stable