Finding the contact force in a hinge?

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SUMMARY

The discussion centers on calculating the contact force in a hinge for a beam system in equilibrium. The beam, measuring 4 meters and weighing 5 kg, supports a 20 kg sign at a 20° angle to the horizontal. The tension in the supporting wire was calculated to be 293.02 N, leading to a hinge force of 291.9 N at an angle of 24.5°. The calculations were verified by resolving the forces into horizontal and vertical components, confirming the system's equilibrium state.

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SopwithCamel
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I have been working on a slightly tricky calculus problem and was hoping someone could verify my solution.

Homework Statement



A 4m long beam whose mass is 5 kg is attached to the wall by a wire and a hinge that allows the beam to rotate. There is a sign (with a mass of 20 kg) attached to the beam. The system is in equilibrium when the beam is at 20° to the horizontal. What is the contact force in the hinge (magnitude and direction)?

Homework Equations



The Attempt at a Solution



I first found the tension in the wire by setting the net torque to zero:
0=|r||T|sinθ + |rs||Fs|sinθ - |rb||Fb|sinθ
(where Fs is the force of the sign and Fb is the force of the beam and rs and rb is the distance of the forces from the hinge, respectively)
0=(4)(T)sin135 - (4)(196)sin110 - (2)(49)sin110
Solving for T, I get the tension in the wire = 293.02 N.

Then, to find the force in the hinge, I found two equations by resolving it into it's vertical and horizontal forces:
Horizontal: Tcos25 = Fcosθ ---> Fcosθ = 265.574N
Vertical: 0 = Fsinθ + Tsin25 - 49 - 196 ---> 245 = Fsinθ + 123.574N ---> Fsinθ = 121.161N

From there, I was able to solve... θ = 24.5° and F = 291.9N.


Is this correct? I hope this isn't asking too much... Please tell me if there are any errors in my figuring.

ALSO ... A quick question: When it says the beam is in equilibrium at 20° to the horizontal, does that imply that it is not at equilibrium at any other point? What exactly does it mean in this scenario to be "in equilibrium"?

Thank you!
 
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This isn't a calculus problem. I've moved the thread to the intro physics forum.
 

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