A uniform 10.0 kg beam 3.0 m long is hinged to a wall...Physics problem, Equilibrium!?
In the diagram below, a uniform 10.0 kg beam 3.0 m long is hinged to a wall and supported by a horizontal rope to make a 40º angle with the wall. A 15 kg mass hangs from the end of the beam. What is the tension in the rope?
Picture of the diagram: http://i47.tinypic.com/xbid69.jpg
Take moments to the beam from the point that is hinged.
Let the tension be T
For equlibrium left hand moments= right hand moments
moment due to tension of the rope = moment due to weight
Tsin50*2 = 15*g*3cos50
T = 15*g*3cos50/(2*sin50)
= 185.2 N
So the tension of the rope is 185.2N