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Precariously Balanced (Posted on 2009-12-22) Difficulty: 3 of 5
Three identical weights are to be suspended from the ends of a rigid light1 "Y"-shaped frame. Each arm of the frame is to be of a different length.

How is this to be accomplished (ie, how do you shape the "Y") so that the 'system' is in equilibrium within a horizontal plane?

















1 "light" is meant as being weightless, having no concern for mass.
Note too, the colours are the radial ring extremeties of the "Y" arms within the horizontal plane.

  Submitted by brianjn    
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Solution: (Hide)
Firstly the sum of the lengths of the shorter arms must be greater than the length of the longest arm.

The task can be simply accomplished with a little geometry and without knowing any angles.

For ease of explanation consider the arms of the "Y" to be the sides of a triangle of lengths in the ratio of a 3-4-5 triangle.

Move the "3" and "4" sides to the same end of the "5" side but keep them parallel to their original position ensuring that they form a "Y".

Consider the extremities of the "Y" as vertices of a triangle. This triangle is also of the ratio of the original triangle with the 'centre' of the "Y" being the centroid of the newly formed triangle.

The requirement then is that the centre point of the arms is to be the centroid of a triangle which can be formed by the extremities of the arms.

Comments: ( You must be logged in to post comments.)
  Subject Author Date
Simplicity?brianjn2009-12-27 23:15:11
re: Three solutionsKenny M2009-12-27 10:48:19
Three solutionsTony2009-12-27 04:00:42
Another general soution methodKenny M2009-12-24 11:17:55
Some ThoughtsSomthing missing in "simple soultion"?Kenny M2009-12-24 10:59:05
SolutionRather Simple SolutionBrian Smith2009-12-23 22:59:57
Some ThoughtsIs this the solution intended?Kenny M2009-12-22 22:25:03
re: Insufficient info to answer?brianjn2009-12-22 22:12:03
Antoehr question - alternative?Kenny M2009-12-22 22:11:02
QuestionInsufficient info to answer?Kenny M2009-12-22 18:45:34
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