What are some Canadian moments in the 1970's?

Principle of moments?? HELP!!?

• Okay, I know that the principle of moments states, that for a body in equilibrium, the sum of the anticlockwise moments about any point is equal to the sum of the clockwise moments about that same point. But...I notice that I have only seen people take the moments about pivots..Do you have to do this?? If so...then why does the rule say about ANY point? If this is not necessary, please explain how it can be taken about ANY point. Eg. if a moment will be clockwise or anticlockwise relative to the point or relative to the pivot. Thnx

• Answer:

  You can chose ANY convenient point about which to take moments. It is often a pivot in simple problems but it doesn't have to be. If there is no rotation, then the principle of moments can be be applied to any point - there is no rotation about the point. You often choose a point at which some unknown force acts (typically a reaction force). The moment of the force is zero about the point, so you can setup an equation without having to first find the unknown force. This is covered in the video-lesson below and is followed by an example. Go to 17min 5sec if you don't want to watch from the beginning.