How do I find the intersection of the wrench's LOA?

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Homework Help Overview

The discussion revolves around determining the intersection of a wrench's line of action (LOA) in a three-dimensional context involving forces and moments. The original poster describes their attempts to calculate the moment using the cross product and expresses uncertainty about applying the relevant equations to find the intersection.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • The original poster attempts to use the moment equation M = Fd and the cross product to find the moment, while questioning how to apply these concepts to determine the intersection of the LOA. Some participants question the clarity of the forces involved and the definition of LOA.

Discussion Status

Participants are actively engaging with the original poster's reasoning, with some suggesting the need for a diagram and clarification on the forces being referenced. There is an acknowledgment of the need for more information to verify the calculations presented.

Contextual Notes

There is a mention of the original poster not providing full details of the question, which limits the ability to check their work. Additionally, the original poster's reference to different forces raises questions about their definitions and symbols.

daisy7777
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Homework Statement
A thin rectangular flat plate is loaded by the forces show. Determine a wrench equivalent force system, and specify the y and z coordinates of the point where the wrench's LOA intersects the yz plane.
Relevant Equations
M = Fd
M = r xF
I've solved for the moment using the cross product where my r = 0i+0.06j+0.03k m and my F = 100i + 150j + 0k. I got my moment to be M= 4.5,3,-6. I know a wrench equivalent force must be parallel to the force (I am assuming this means the resultant force in this case), but how do I apply that logic to fid the intersection? I assume I am meant to use the formula M=Fd where F = 300i, 0j, 0k but I am not sure if this is even applicable in this question as it is in 3D.

All in all, I would just like a little push in the right direction.
 
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daisy7777 said:
Homework Statement: A thin rectangular flat plate is loaded by the forces show. Determine a wrench equivalent force system, and specify the y and z coordinates of the point where the wrench's LOA intersects the yz plane.
Relevant Equations: M = Fd
M = r xF

I've solved for the moment using the cross product where my r = 0i+0.06j+0.03k m and my F = 100i + 150j + 0k. I got my moment to be M= 4.5,3,-6. I know a wrench equivalent force must be parallel to the force (I am assuming this means the resultant force in this case), but how do I apply that logic to fid the intersection? I assume I am meant to use the formula M=Fd where F = 300i, 0j, 0k but I am not sure if this is even applicable in this question as it is in 3D.

All in all, I would just like a little push in the right direction.
Since you have not posted the details of the question, it is impossible to check your work. In particular, you do not explain how you obtained that vector for r.
 
@daisy7777, note what @haruspex said in Post #2. And a diagram is needed.

You have written "F = 100i + 150j" + 0k and "F = 300i, 0j, 0". If you are referring to two different forces the meaning of each must be clear and they should have different symbols.

If you are not familiar with the method, try watching the short (~5 mins) video here
 

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