posted by sweety on .
the figure shows a uniform beam of weight 420 N and length 2.0 m suspended horizontally. On the left it is hinged to a wall, on the right it is supported by a cable bolted to the wall at distance D above the beam. The least tension that will snap the cable is 1100 N. What value of D corresponds to that tension? the figure cant be posted bt its like a right angle triangle on vertical side its wall, base side has the beam and hypotenuse is the string.
I assume that the cable (string) is bolted to the same wall, on the left. The angle of the string from horizontal is
A = arctan (D/2). Weight acts at the middle of the beam. Set the moment about the hinge equal to zero to get the cable tension, T.
420*1.0 m = T * sin A * 2.0 m
T = (1/2)* 420/sin A = 1100 (at the breaking point)
sin A = 210/1100 = 0.1909
A = 11.0 degrees
tan A = 0.1945 = D/2
D = 0.389 m