# Physics V Beam Problem

1. Nov 28, 2013

### djMan

1. The problem statement, all variables and given/known data

Two identical, uniform beams weighing 260 N each are connected at one end by a frictionless hinge. A light horizontal crossbar attached at the midpoints of the beams maintains an angle of 53.0 ∘ between the beams. The beams are suspended from the ceiling by vertical wires such that they form a "V", as shown in the figure

What force does the crossbar exert on each beam?

What is the magnitude of the force that the hinge at point A exerts on each beam?

What is the direction of the force that the hinge at point A exerts on the right-hand beam?

What is the direction of the force that the hinge at point A exerts on the left-hand beam?

2. Relevant equations

Ʃτ = 0
ƩF = 0

3. The attempt at a solution

I have tried to sum the torques and solve for the force of the bar however I end up getting a fraction with a zero numerator. I don't really know how to "see" this problem even after drawing it.

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2. Nov 28, 2013

### tiny-tim

hi djMan! welcome to pf!
shouldn't do

3. Nov 28, 2013

### djMan

Ok,

Let L = length
T = tension of each wire
Fbar = force exerted by bar

Well what I have so far is:

Net torque about hinge = Tsin(153.5)L - Fbar * sin(63.5)L/2 - Tsin(153.5)L + L/2*Fbar*sin(63.5) = 0

And I get a zero each time I try to solve for Fbar

4. Nov 28, 2013

### djMan

Hi everyone, I actually found out how to do this problem. Given the fact that everything is in equilibrium I can cut the "V" in half and look at each side using torque. Then I can solve for Fbar without getting a zero for an answer. Lol mastering physics...

5. Nov 29, 2013

### tiny-tim

hi djMan!

(just got up :zzz:)
yes …

as you've probably realised, if you're finding a tension, you have to "cut in half" the thing with the tension before you do your free body diagram, otherwise the tension occurs twice, as a pair of internal forces, which of course add to 0