A 3.0 N picture is hung by a nail with a loose string that makes an equilateral triangle with the edges of the frame. ( The nail and two sides of the picture form a triangle.) What is the tension in the string? (Hint: the nail acts like a pulley and each piece of string on each side of the nail holds 1/2 of the picture weight.)
The tension in the string is T = mg/(2sin(60)) = 3 / (2sin(60)) = 1.73 N.