Moment for bending materials test

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Discussion Overview

The discussion revolves around calculating the moment (M) for a bending materials test in a practical assignment. Participants are exploring how to derive M based on the provided information and the setup of the experiment, which involves weights and distances.

Discussion Character

  • Homework-related
  • Mathematical reasoning
  • Technical explanation

Main Points Raised

  • One participant expresses uncertainty about calculating the moment (M) and suggests it relates to the mass of the weights and their distance from the supports.
  • Another participant notes that M is constant over a specified length (400 mm) and inquires about calculating reactions at specific points.
  • A different participant discusses the relationship between the applied moment and the weights, questioning whether it should be calculated as W multiplied by different distances (100 mm, 300 mm, etc.).
  • One participant provides a definition of moment and suggests that at the point of load application, the moment is zero, while proposing that in the central section, it could be calculated as W multiplied by 300 mm.

Areas of Agreement / Disagreement

Participants do not reach a consensus on the exact calculation of the moment, with multiple competing views on how to derive it based on the weights and distances involved.

Contextual Notes

The discussion highlights missing information regarding the specific distances and weights needed for accurate calculations, as well as the dependence on the definitions of moment being used.

scotty03
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Homework Statement


I have to do the following practical, but I am unsure of how to calculate one of the variables.

We are doing this test
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and we are given this information to calculate E.

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I have equations on how to calculate R and I, but I am not sure how to calculate M. It's obviously something to do with the mass of the weights on the end and the distance from them, but this information isn't included in the prac sheet.

Does anyone have any ideas?
 
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In the 400 mm length, M is constant. Are you able to calculate the reactions, where the little triangles are?
 
They both = W from sum of forces in Y direction.

The idea of the test was to see how much the material deflected upwards in the middle. I am just not sure if the applied moment is W*100mm or W*100mm*2 or W*300 or W*300*2
 
One definition of Moment at a section is: The sum of the moments on one side (or the other) of the section. So, at the point of application of the load at the end, you should find the moment is zero. In the central section it is W*300. You should check this by considering a section distance x from the left hand support, going to the right.
 

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