# Homework Help: Beam on two shapes

1. Dec 28, 2013

### Numeriprimi

Homogeneous beam shaped in letter L is suspended on two ropes of the same length l.
The beam is of negligible thickness and its longer arm is three times longer than the shorter arm. Its overall length is l as well as the length of one rope. Look at each situation in the figures. How can I determine the forces acting on the rope at points A and B in both situations?
There is picture on first example: http://fyzikalniolympiada.cz/archiv/55/fo55a1_z.pdf

I really don't know, how to do it. Gravitational force acts on the beam, OK... And I have to
decompose the force on the beam. But how? What is different in the two situations? I don't know...
May I can decompose in ratio 3:1.
I solved a example where was a weight on two ropes and I must to determine the forces on ropes like on pictures of second example (http://fyzikalniolympiada.cz/archiv/54/fo54d1_z.pdf). However, I think it was easier... Is the example with beam similar? I really don't know more, sorry... Please, give me a advice and sorry for my English.

2. Dec 28, 2013

### haruspex

You know the total vertical force in each case, right? What equation does that give you?
Try taking moments about one of the ends of the beam.
Please post whatever equations you can develop.