Shear and Moment Diagram Equations

[jdawg]

Homework Statement

Write the shear and moment diagram equations and graph them.

Homework Equations

The Attempt at a Solution

I attached my attempted solution in a pdf (I know the last section of the moment diagram is supposed to be parabolic, I accidentally drew a straight line instead). I can't figure out what I'm doing wrong. When I use the method where you just calculate the areas of the shear diagram to get the moment diagram, I get the correct answer. But when I use my moment equation I get 180 instead of 90. I feel like I've had previous problems where my answer was off by a factor of 2. I would really appreciate if someone could catch where I'm making a mistake!

 

[Dr.D]

It appears to me that your shear diagram is incorrect. The reaction at the left end is upward, so the diagram should initially start positive. See if that helps.

 

[jdawg]

Sorry its kind of hard to see in the pdf, but its -6.25 kip. I should have just drawn it downward instead of tacking on a negative sign.