Components of the equivalent moment at a point

In summary, the conversation was about finding the x, y, and z components of the equivalent moment at point A in two diagrams. For the green block, the y and z components of the equivalent force at point A were found to be -39.04kN and 15.48kN respectively. However, for the first question, the calculated x component was incorrect at 26.836kN-m. The same approach was used for the second question, but the x component was found to be 1300N-mm, which was also incorrect. The individual was unable to figure out the correct solution and requested for assistance.
  • #1
Davidf77
1. The problems:
Screen Shot 2017-09-21 at 5.34.33 PM.png
Screen Shot 2017-09-21 at 5.34.45 PM.png
Screen Shot 2017-09-21 at 5.34.33 PM.png
Screen Shot 2017-09-21 at 5.34.45 PM.png

Screen Shot 2017-09-21 at 5.34.33 PM.png
Screen Shot 2017-09-21 at 5.34.45 PM.png


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.
 
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  • #2
Davidf77 said:
found the x component to be 26.836kN-m,
That is not what I get. Please post the details of your working.
 
  • #3
haruspex said:
That is not what I get. Please post the details of your working.

Yeah I know that's wrong. This is my work, I just really can't figure it out
IMG_1821.JPG
IMG_1820.JPG
 
  • #4
Davidf77 said:
Yeah I know that's wrong. This is my work, I just really can't figure it out
View attachment 211537View attachment 211538
That's too messy.
My response singled out one datum, the x component you calculated for the torque on the green block. Please post just your calculation of that, taking the trouble to type your working in, not uploading an image.
(Images are for textbook extracts and diagrams.)
 

Related to Components of the equivalent moment at a point

What are the components of the equivalent moment at a point?

The components of the equivalent moment at a point refer to the forces that act on an object at a specific point and cause it to rotate around that point. These forces include the magnitude, direction, and location of the force acting on the object.

How do you calculate the magnitude of the equivalent moment at a point?

The magnitude of the equivalent moment at a point can be calculated by multiplying the force by the distance from the point to the line of action of the force. This can be represented by the equation M = F * d, where M is the magnitude of the moment, F is the applied force, and d is the distance from the point to the line of action.

What is the direction of the equivalent moment at a point?

The direction of the equivalent moment at a point is perpendicular to the plane formed by the point and the line of action of the force. This direction is determined by the right-hand rule, where the fingers of your right hand point in the direction of the force and your thumb points in the direction of the moment.

Why is it important to consider the location of the force when calculating the equivalent moment at a point?

The location of the force is important because it affects the magnitude and direction of the equivalent moment at a point. A force applied at a greater distance from the point will result in a larger moment, while a force applied at a different angle will result in a different direction of the moment.

How are the components of the equivalent moment at a point used in real-world applications?

The components of the equivalent moment at a point are used in various engineering and physics applications, such as designing structures and machines. Understanding these components allows engineers to calculate and predict the effects of forces on an object and ensure the stability and safety of their designs.

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