Stability of equilibrium

BLUE_CHIP

A uniform triangular lamina ABC where AB = 1m and BC = 2m and it is right angled at B. It is suspended from C and hangs freely under gravity. Calculate the angle between BC and the downwards vertical.

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HallsofIvy

Homework Helper
Find the center of gravity of the lamina.
The center of gravity will hang directly below C.

Easy way to find the center of gravity: Set up a coordinate system so that B is at (0,0), A is at (0,1), C is at (2, 0). Take the "average" of the three points. Find the slope of the line through (2,0) and the center of gravity and remember that slope = tan of angle the line makes with BC (x-axis).
(I get a remarkably simple result!)

(Off the subject: I once had a professor who put (on the FINAL exam!) the question "What is "lamina" spelled backwards?"! One student got really angry with him because the question "didn't make sense".)

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