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Homework Help Overview

The discussion revolves around a lever problem involving a beam with specific weights and support reactions. Participants are attempting to calculate the support reactions for a 33m beam that has two supports, overhangs, and various forces acting on it.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • Participants are discussing the setup of the problem, including the placement of forces and the calculation of torques. There are questions about where individuals are getting stuck and the reasoning behind their calculations.

Discussion Status

Some participants have provided insights into the calculations and have pointed out potential misinterpretations of the problem setup. There is an ongoing exploration of the forces involved and their implications on the beam's stability, with no explicit consensus reached yet.

Contextual Notes

Participants note discrepancies in the total downward and upward forces, suggesting a potential issue with rounding in the distributed force calculation. There is also mention of the challenges posed by interpreting information presented in photographs.

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Summarizing the problem in text avoids making people squint at photographs.

33m beam has two supports
overhangs both by 5m
600kN at extreme right end
900kN at extreme left end
159kN/m over entire length
Calculate support reactions.
...

You seem to have worked the torques...
Where did you get stuck? Work slowly through the math - showing your reasoning.
 
I don't know where I am getting stuck, but I aint getting the answer. I am not sure what I am doing wrong.. I've tried so many different combinations.. obviously the basis for the formula is clockwise movements=counterclockwise movements, but I aint getting the answer.. and 900kN is not at the extreme left end, its 8m from the left end.
 
Oh I misread that - see the problem with presenting the problem in a photograph?

I'm having trouble treading your working in the photo - I see a 900x8 in there ... that would be the torque about the extreme left end from the 900kN point force. But there is no pivot there: the pivot is 5m, in from that end.

You can reality check your answer by noticing that the total downward force has to equal the total upward force (the beam ain't going anywhere.)

Mind you - taking a look at the answers they give (3297kN and 3453kN) I see they add up to 6750kN upwards... the total downwards force is 6747kN, suggesting that the beam will lift off under a net unbalance 3kN.

I think the distributed force was supposed to be 159.09kN/m ... and somebody rounded off when they shouldn't have.
 

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