Newton's Laws (20分)

Because of the rotation of the Earth, a plumb bob may not hang exactly along the direction of the Earth's gravitational force on the plumb bob but may deviate slightly from that direction.
a) Show that the deflection A in radians at a point at latitude L is given by

A = sin2L[(2(pi^2)R)/(gT^2)]

where R is the radius of the Earth and T is the period of Earth's rotation.