- #1
nothingsus
- 16
- 0
Homework Statement
ignore all the other writing!
The Attempt at a Solution
I can't tell where I'm making a mistake. Probably a massive oversight somewhere but I don't know where!
First find the reaction forces at the pin and roller by treating everything as a rigid body. (I am now aware this isn't necessary since I can start at joint D since one of the equations has 1 unknown, but this method is still bugging me)
sum F_x = 0
R_Dx + R_Ax - 5000sin(15) = 0 (equation 1)
sum F_y = 0
-R_Ay - 5000cos(15) = 0
so R_Ay = -4829 N
sum Moments about point A = 0
(2*R_Dx) - (5*5000sin(15)) = 0
so R_Dx = 3235 N
so plugging R_Dx into equation 1 gives
R_Ax = -1941 Nstarting at joint D
sum F_x = 0
R_Dx + BD = 0
so BD = -R_Dx = -3235 N
but the answer says it is 12.89 kN compression!
I can't continue because everything else will be wrong.
What am I screwing up on?