A simple pendulum consists of a mass m suspended from a fixed point by a weight-less, extension less rod of length l. Obtain the equation of motion and, in the approximation that sin θ ≡ θ, show that the natural frequency is w0 = √g/l, where g is the gravitational field strength. Discuss the motion in the event that the motion takes place in a viscous medium with retarding force 2m√gl θ.