- #1
martix
- 162
- 1
Well, not that simple. Try isolating BCD and take FBD's of members BC and CD. Note that there can be no moments at joints B, C, and D. Solve for the reactions at B and D, then analyze AB as a cantilever with a distributed load and concentrated load at the far end. Assume small deflections. Note that your units for F are stated incorrectly, it should be in kN, not kN-m.martix said:Come on? Cant anyone help me? This ought to be simple, but surprisingly no one knows.
I don't know what numbers you are getting because you haven't shown your work, but if you get negative numbers it might just mean that you assumed the wrong direction for the reactions at A and D, or, if the solution was given to you with a negative value, it might just mean that the direction of the force at the end point reaction is down. Perhaps you can visualize that the couple produced by the equal but opposite forces, F, tend to attempt to rotate frame BCD counter clockwise, resulting in a downward reaction at D and an upward reaction at A. Also note that at A, there must be a reactive moment acting at that end point.martix said:I am not familiar with everything the exact English terminology so there may be small discrepancies in what I'm trying to say.
Anyway, didn't notice the F units thing...
Well I do know that the directions do no matter for the internal joints, all that is important is that they are opposite for each joint so as to keep the equilibrium.
The problems I'm trying to solve are usually only about finding the magnitude, they don't involve vector quantities. So that's why I need to determine the direction(i.e. sign in the equilibrium equation) of the forces on the end points. Which for this case are A and D.
But then again - the solution has some negative numbers which don't really make sense to me.
Anyway, thanks.
Static equilibrium is a state in which all forces acting on an object are balanced, resulting in no overall change in the object's motion or position.
To determine static equilibrium reactions, you must first identify all the external forces acting on the object and their directions. Then, using the equations of static equilibrium, you can calculate the magnitude and direction of the reactions at the points where the object is supported.
The equations of static equilibrium are: ΣFx = 0 (sum of horizontal forces equals zero), ΣFy = 0 (sum of vertical forces equals zero), and ΣM = 0 (sum of moments equals zero).
Yes, the center of gravity can be outside of an object if the object has an irregular shape or if the distribution of mass is not symmetrical.
Static equilibrium refers to a state where all forces acting on an object are balanced and there is no overall change in motion or position. Dynamic equilibrium, on the other hand, refers to a state where an object is in motion with a constant velocity, meaning that all the forces acting on the object are balanced but the object is still moving.