Chapter 1.3, Problem 31P

(a)

To determine

To show: That the angular momentum about the point of support is given by $M=m{L}^2\frac{d\theta }{dt}$.

(b)

To determine

To show: That the resulting equation obtained by setting $\frac{dM}{dt}$ to the moment of gravitational force reduces to $\frac{d^{2}E}{d{t}^2}+\frac{g}{L}\sin \theta =0$.