- #1
Davidf77
1. The problems:
The questions are to find the x, y and z components of the equivalent MOMENT at point A in both diagrams.
For the green block, I found the y and z components of the equivalent force at point A are -39.04kN and 15.48kN respectively.
For the first question (the green block) I attempted to find a solution by crossing the unit vectors with the forces at each place the force is acting on. Then I subtracted 75 from the x component due to the moment of 75kN-m. I found the x component to be 26.836kN-m, the y to be 9.68kN-m, and the z to be 234.24kN-m. These are all wrong. I tried summing moments several different ways and every way I tried was wrong.
For the second question (the blue thing) I used the same approach as the last one, crossing the unit vectors with the forces at each place the force is acting on. I got 1300N-mm for the x component, 127800N-mm for the y component, and -40200N-mm for the z component. These are all wrong as well.
There is a third question that is the same concept as these two and I used the same approach for that and my answers for that one were all correct, so I don't know what I am doing wrong for these two.
The questions are to find the x, y and z components of the equivalent MOMENT at point A in both diagrams.
For the green block, I found the y and z components of the equivalent force at point A are -39.04kN and 15.48kN respectively.
The Attempt at a Solution
For the first question (the green block) I attempted to find a solution by crossing the unit vectors with the forces at each place the force is acting on. Then I subtracted 75 from the x component due to the moment of 75kN-m. I found the x component to be 26.836kN-m, the y to be 9.68kN-m, and the z to be 234.24kN-m. These are all wrong. I tried summing moments several different ways and every way I tried was wrong.
For the second question (the blue thing) I used the same approach as the last one, crossing the unit vectors with the forces at each place the force is acting on. I got 1300N-mm for the x component, 127800N-mm for the y component, and -40200N-mm for the z component. These are all wrong as well.
There is a third question that is the same concept as these two and I used the same approach for that and my answers for that one were all correct, so I don't know what I am doing wrong for these two.
