A picture frame hung against a wall is suspended by two wires attached to its upper corners. If the two wires make the same angle with the vertical, what must the angle be if the tension in each wire is equal to 0.75 of the weight of the frame? (Ignore any friction between the wall and the picture frame.)
1 Answer
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T1 = T2 = 0.75mg
T1 * cos(α) + T2 * cos(α) = mg
2 * T1 * cos(α) = mg
2 * 0.75mg * cos(α) = mg
3/2 * cos(α) = 1
cos(α) = 2/3
α = cos^-1(2/3)
α = 48.2 degrees to three significant figures.
