Solve Static Equilibrium: Beam, 520N Force, Cable Tension

Click For Summary
SUMMARY

The discussion focuses on solving a static equilibrium problem involving a vertical beam subjected to a horizontal force of 520N and supported by a cable. The beam has a mass of 40kg and is 5m tall, with the cable attached at a height of 3m and forming an angle of 28 degrees with the ground. Key equations used include ΣFx = 0, ΣFy = 0, and Στ = 0, which are essential for calculating the tension in the cable and the reaction forces at the ground. The participant expresses confusion regarding the forces acting on the beam, particularly the need for friction and the contradiction in torque calculations.

PREREQUISITES
  • Understanding of static equilibrium principles
  • Knowledge of free body diagrams
  • Familiarity with torque calculations
  • Basic mechanics of forces and tension in cables
NEXT STEPS
  • Calculate the tension in the cable using the correct static equilibrium equations
  • Explore the role of friction in static equilibrium problems
  • Review examples of free body diagrams in similar contexts
  • Study the implications of torque in static systems
USEFUL FOR

Students studying physics, particularly those focusing on mechanics and static equilibrium, as well as educators looking for practical examples of force analysis in beams and cables.

MPat
Messages
15
Reaction score
1

Homework Statement


A uniform vertical beam of mass 40kg is acted on by a horizontal force of 520N at its top and is held, in the vertical position, by a cable as shown.
a) Draw a free body diagram for the beam, clearly labelling all the forces acting on it
b) Calculate the tension in the cable.
c) Determine the reaction forces acting on the beam by the ground.

Homework Equations



ΣFx = 0

ΣFy = 0

Στ = 0

The Attempt at a Solution


a) I can't seem to add images to this. Whenever I try it only gives me the option of adding an image url which I don't have. Maybe someone can tell me how to do that!

For the image provided the uniform beam is standing up right (height of 5m). Force applied (520 N) acts on the top end of the beam to the left. A cable attaches the beam from 3m height down to the ground on the right. The angle between the ground and the cable is 28degrees.

In my free-body diagram I have the following forces acting on the beam.
Fa = 520N
Force tension from the cable
mg
Fn

Am I missing a force here? Should there be a force of friction between the beam and the ground? The question does not explicitly state anything about that.

b)
ΣFx = Ftx - Fa = 0

ΣFy = Fn-mg-Fty=0

Στ = Fa * 2 = 0
where the axis is located where the cable attaches to the beam at 3m. Ft does not create a torque force as it acts at the axis, and mg and Fn also do not create a torque force as the act directly away from the axis

I get here and I realize something is missing...based on the torque equation Fa would = 0, but Fa is given as 520N. Here's where I'm confused.

Please help!

Thanks
 
Physics news on Phys.org
To add an image, you can try putting your image in a Word document, say, and then "cut" the image from the document and "paste" the image into your post. Or, when entering a post, you should see an "upload" button that you can use to upload a picture that is stored as a file on your computer.

You can see that your torque equation leads to a contradiction. So, maybe you were on the right track when you were wondering if friction between the beam and the ground should be included. Note that the question asks for the reaction forces on the beam by the ground.
 
Use the upload button then the insert thumbnail or full size.
 

Similar threads

  • · Replies 10 ·
Replies
10
Views
3K
Replies
43
Views
3K
  • · Replies 5 ·
Replies
5
Views
5K
  • · Replies 6 ·
Replies
6
Views
4K
Replies
12
Views
4K
  • · Replies 6 ·
Replies
6
Views
3K
  • · Replies 6 ·
Replies
6
Views
4K
  • · Replies 9 ·
Replies
9
Views
5K
Replies
4
Views
2K
  • · Replies 10 ·
Replies
10
Views
6K