In a contraption built by a fraternity, a person sits at the center of a swinging platform...

In a contraption built by a fraternity, a person sits at the center of a swinging platform with weight Wp = 800 lb and length L = 12 ft suspended via two identical arms each of length H = 10 ft and weight Wa = 200 lb. The platform, which is at rest when θ = 0, is put in motion by a motor that pumps the ride by exerting a constant moment M in the direction shown whenever 0 ≤ θ ≤ θp while exerting zero moment for any other value of θ.

Figure P8.26

Neglecting the mass of the person, neglecting friction, letting M = 900 ft·lb, and letting θp, = 25°, find the minimum number of swings necessary to achieve θ > 90° and the ensuing speed achieved by the person at the lowest point in the swing. Model the arms AB and CD as uniform thin bars.