PURPOSE: To verify the equation for torques when the center of mass is outside the object.
DESCRIPTION: A bracket is bent into a right triangle with arms of length a and 2a, and suspended from the end of the small arm as photographed. What is the angle of repose r of the small arm with the vertical, at equilibrium?
From the equation of torques, w1 x1 = w2 x2,
where: w1= mg and x1= a/2 sin r,
also: w2 = 2mg and x2 = a cos r - a sin r)
From these, tan r = 4/5, and r = 38.66 degrees.
REFERENCES: (PIRA unavailable.)
EQUIPMENT: Right angle bracket, plumb bob, and protractor, pre-assembled as shown.
SETUP TIME: None.
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