DISCUSSION THREAD
Reminder/hints: Please note that member DK is a two-force member, since there are forces acting on the member at only points K and D. This observation tells us the line along which the reactions on the member act. Take advantage of this insight as you draw the individual FBDs of the two members.
Any questions? Ask (and answer) questions here.
When we pick a point to draw shear at, say the left side of C, does it matter whether we draw the shear force vector pointing up, or pointing down? In the lecture, we did example 1.3 which had the shear on the left face of G pointing down. But in example 1.5 on youtube, the left face had the shear drawn facing up.
At this point, there is no need to follow a particular sign convention. If, for example, you draw the shear force V downward, and you get a negative sign, it simply means that it V is actually pointing upward. That is the role of signs here.
Later on in the course, when we draw our shear force/bending moment diagrams, then we will stick with a particular sign convention so that we can construct the diagrams that are independent of the side of the cut on which the shear force is drawn..
I don't think it would matter as long as your signs stay consistent with your defined axis and FBD.
Should we leave our answers in terms of the force from the two-force member or should we solve for that force?
Your answer should be in terms of given variables, P0 and R
When we solve for the force at K, we get a single force in the direction between the two points of the 2-force member. Do we need to split the term into its x and y components or can we leave it as is, with the sign indicating compression or tension?
You may leave it as a single force directed along line DK, or you may write it in its x- and y-components. Either way.