Why is a fulcrum normally triangular?

Singapore
May 9, 2010 9:28am CST
My mum is trying to teach on levers and there is this particular worksheet she has to get her kids to fill up. But there aren't any answers given. In this worksheet, there are 3 diagrams. All has the simple lever simple. HOwever, each pivot point is different. One is a triangular pivot, the second is a square pivot and the third is a cylindrical (circle) pivot. And the question is which pivot can lift the heavy object most easily and why? I know the answer is the triangular pivot. But i don't know the explanation. The 2nd question is which pivot is the hardest to lift the heavy object and why? I was thinking it should be the circle pivot as there no base and the lever system won't work. Can you guys help.
2 responses
@kar295rocks (2119)
• India
9 May 10
The answer is a triangular fulcrum. It is because in the case of a triangle, there is only one meeting point between the lever and the fulcrum. So if the center of gravity of the lever is rested on the fulcrum, the object can be lifted easily. If it has more than a side on the top [place of meeting between lever and fulcrum], the lever will roll out or will be unable to lift. It is the toughest in the case of circular pivot as the system does not rest completely.
1 person likes this
• Singapore
9 May 10