Question

1)How can the CG of an irregularly shaped object be determined?
2) What is the lever arm of a force?
3) In what direction should a force be applied to produce maximum torque?

Answer 1

1) Hang it by a string from different points on the outside. The intersection of extended lines defined by the string will be at the CG

2) The distance from the axis of rotation to the point of force application. Think of a wrench. The distance from the bolt/nut axis to the hand is the lever arm.

3) Perpendicular to the lever arm.