Finding the reaction of a beam

In summary, the conversation is discussing a beam with a negligible weight and a mass of 70kg at its end, hinged to a vertical wall and held at an angle of 30 degrees by a light cable of 5mm diameter. The question is about finding the reaction of the beam at the wall and determining the Young's Modulus of the cable. The suggested method is to take the moments about point A and use Hooke's Law to calculate the modulus. The person asking for help has not been taught how to do this and is looking for a worked example to understand the formula and method.
  • #1
farheld
3
0
1. A Beam of negligible weight AB, carrying a mass of 70kg at its end B, is hinged to a vertical wall at A and held at B 30degrees to the vertical wall by a light cable BC of 5mm diameter, C is at a distance vertically above A

Find the reaction of the beam at the wall and predict the behaviour of the cable by determining its Young;s Modulus if it is not allowed to extend more than 0.1% of its length under any condition




2. Stuck on what equations i need to use for the above



3. I drew the diagram in question and that's as far as i got =/

http://img201.imageshack.us/img201/1646/problemib2.jpg
 
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  • #2
Did you try to sum the moments about A?
 
  • #3
FredGarvin said:
Did you try to sum the moments about A?

Sorry, i don't have any idea what you're talking about =/
 
  • #4
Fred is talking about taking moment or torque about A, the second condition of static equilibrium.

I would imagine you have to find the force along the cable and then use Hooke's Law in order to calculate the Young's Modulus or Modulus of elasticity.
 
  • #5
I still havn't been able to get my head round it.

Thing is, i havn't been taught how to do it, therefore i don't understand the terms you are using.

I need maybe a worked example of something similar that i can understand the forumla to use and the method of working it out.

Thanks,

Joel
 
  • #6
Go through the statics tutorials.

http://web.umr.edu/~bestmech/
 
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1. How is the reaction of a beam calculated?

The reaction of a beam is calculated using the principles of statics and equilibrium. This involves analyzing the external forces acting on the beam, as well as the internal forces within the beam itself. By setting up and solving equations of equilibrium, the reaction forces can be determined.

2. What factors affect the reaction of a beam?

The reaction of a beam can be affected by various factors such as the material and dimensions of the beam, the type and magnitude of external forces applied, and the support conditions at each end of the beam. Additionally, factors such as temperature changes and loading history can also impact the reaction of a beam.

3. Why is it important to find the reaction of a beam?

The reaction of a beam is an essential part of structural analysis and design. It helps to ensure that the beam can support the applied loads without failure or excessive deflection. This information is crucial for ensuring the safety and stability of a structure and can also influence the materials and dimensions chosen for the beam.

4. What are the different types of reactions a beam can have?

A beam can have different types of reactions depending on the support conditions at each end. These include fixed (or built-in) support, simply supported, cantilevered, and overhanging. Each type of reaction produces a unique pattern of internal forces within the beam.

5. Can computer software be used to find the reaction of a beam?

Yes, there are various structural analysis software programs available that can calculate the reaction of a beam. These programs use mathematical models and algorithms to simulate the behavior of the beam under different loading and support conditions. However, it is still important for engineers to have a thorough understanding of the principles involved in finding the reaction of a beam in order to properly interpret and utilize the results from these software programs.

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