Beam deflection

1. Jul 21, 2016

1. The problem statement, all variables and given/known data
for the circled part, why the why the author didnt include -12(9)kNm moment in the equation of moment ?
[PLAIN]http://imgur.com/a/l3Bu4[URL]http://imgur.com/a/l3Bu4[/URL] [Broken]
2. Relevant equations

3. The attempt at a solution
IMO, the author should include it in the equation, am i right?
So, M= -258+52<x-0>-(0.5)(8)(<x-0>^2)+50+(0.5)(8)(<x-5>^2)-12(9) ?

Last edited by a moderator: May 8, 2017
2. Jul 21, 2016

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3. Jul 22, 2016

did the author miss out something?

4. Jul 27, 2016

pongo38

The figure does not include the variable 'x'. But, wherever you put it in the range 0 to 9 m, what contribution to Mx do you think the 12 kN force would make? Recall one definition of moment that it is the algebraic sum of moments on ONE side of a section.

5. Jul 27, 2016

The force 12kN only will cause moment at x just 9m, no moment generated at x less than 9m....
But, I still couldn't understand why the moment 12(9) is not included?

6. Jul 27, 2016