What are the cord tension and force on the hinge for this angled beam?

  • Thread starter Thread starter hangingwire
  • Start date Start date
  • Tags Tags
    Angle Beams Wires
AI Thread Summary
The discussion focuses on calculating the cord tension and hinge force for an angled beam weighing 10 kg and measuring 8.0 m in length. The user attempts to find the torque on the wire and questions whether a horizontal force exists due to the beam's angle. They derive an equation involving torque and tension but initially miscalculate the tension, thinking it might be double the expected value. After clarifying the role of angles in torque calculations, they conclude that the weight of the beam acts vertically, and the tension can be correctly determined as 49 N. The final understanding emphasizes that the beam's weight does not require additional horizontal components in the calculations.
hangingwire
Messages
8
Reaction score
0

Homework Statement


Find cord tension and force on the hinge on this beam given the following:

Picture of the equation (in attachments)
beam is 10 kg
beam is 8.0m long

Homework Equations



[T=0
[F=0

[h2]The Attempt at a Solution[/h2]

Finding the Torque on the wire...
I attached my FBD I drew. Before I start, one question? Since the beam is on an angle, would there be a horizontal force on the x-axis resulting from the Mass of the beam? If so, It could be 60 degrees? Mg Sin60?

That is my attempt using the "Z-rule" in angles

Anyways:

[T= 0
Tcw = Tccw
mg(d) = Tsin( ) * (d)
(10)(9.8)(4) = T sin30 * (8m) ----> Sin 30* given that directly across is 90 degrees + 60 degrees given = 30 degrees left at where the beam and wire are attached.

392N = T sin30 * (8m)

392N divided by 8m = 49

49 = T sin30

49 divided by sin30 --> 98?

The answer is 49N. Why did I get double the answer? Is there something with my angles?
 

Attachments

  • Beam1.jpg
    Beam1.jpg
    7 KB · Views: 524
  • Beam2.jpg
    Beam2.jpg
    4.5 KB · Views: 532
Physics news on Phys.org
The weight of the beam acts at angle to the "arm", so its torque must involve the sine of the angle. Intuitively that should be fairly clear: the "more vertical" the beam gets, the easier it is to hold it in place.
 
So instead of "Mg" just being "Mg". It is "Mgsin(30)"? Is that what you are trying to say? If I change that in my equation it works out?

If that is the case, waste no time to say... Would the horizontal axis on Mg also require a MgCos(30) to workout the force from the hinge in components?
 
It should be fairly obvious that 49 sin 30 = T sin 30 implies T = 49.

Regarding the forces, the answer is no. If you you use the horizontal and vertical axes, then the weight is purely vertical - it always is; the other forces, however, are not.
 
Figured it out! Thanks
 
Last edited:
Thread 'Collision of a bullet on a rod-string system: query'
In this question, I have a question. I am NOT trying to solve it, but it is just a conceptual question. Consider the point on the rod, which connects the string and the rod. My question: just before and after the collision, is ANGULAR momentum CONSERVED about this point? Lets call the point which connects the string and rod as P. Why am I asking this? : it is clear from the scenario that the point of concern, which connects the string and the rod, moves in a circular path due to the string...

Similar threads

Back
Top