Posted by Anonymous on .
A circular shop sign of mass 10kg is to be hung from the wall of the shop.
The sign hangs from a light, rigid horizontal support of length 0.48m that is hinged to the wall at one end A. The other end B of the support is attached by a model string to a point C at a distance 0.2m vertically above the point A. You may model the sign as a particle located below the midpoint of the horizontal support AB.
By taking torques abut the hinged end A, and considering equilibrium of the beam, find the tension in the rope.

Physics 
bobpursley,
a. label the forces at the supports, and the hanging end.
Here it is in my head:
the angle at the rope to horizontal is Theta. W is the weight of the sign. T is tension.
Torque about A:
Tension*Lengthstring*cosThetaWeight=0
but cosTheta= .48/lengthstring