Calculate The Moments about the Point A, [Guidance needed]

In summary, the conversation is about a student seeking guidance on how to solve a physics exercise involving calculating the moments about a point A. The exercise includes a visual representation with a common A(PIN)---B(ROLLER) element, two forces going down (5 kips and 2 kips), and distances about points A and B (6 ft-8ft-10ft). The student attempted the solution but is unsure if it is correct and requests for others to provide their input. The conversation also touches upon the concept of equilibrium, the role of the roller, and the possibility of an additional force at point A. The student is seeking clarification and guidance on how to approach the exercise and mentions that the problem may be simpler than initially
  • #36
Dellis said:
So that is the answer to the problem?, showing all the calculated moments, you don't need to add them or anything like that?, just show that?

Based on the question you asked...yes. Those are the moments about A.

CS
 
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  • #37
stewartcs said:
That does not sum to zero.

The negative sign in front of 2(24) should not be there based on your sign convention.

CS

Ok so this below and the "Moments about A" calculation equal to= 0 as stated above?, that is the answer to all of this?

[tex]\Sigma{M_A} = 5(6) - 5.57(7) + 2(24) = 72.43 kips/ft [/tex]


5(6) = 30 ft-lb
-5.57(14) = -78 ft-lb
2(24) = 48 ft-lb
---------------------
Sum = 0 ft-lb
 
Last edited:
  • #38
Dellis said:
Ok so this is? and the "Moments about A" equal to 0 as stated above?, that is the answer to all of this?

[tex]\Sigma{M_A} = 5(6) - 5.57(7) + 2(24) = 72.43 kips/ft [/tex]


5(6) = 30 ft-lb
-5.57(14) = -78 ft-lb
2(24) = 48 ft-lb
---------------------
Sum = 0 ft-lb

No.

-5.57(7) is not correct...it should be, as stated numerous times above, -5.57(14). The 14 comes from 6 + 8 which is the distance between point A and reaction B.

CS
 
  • #39
The answer is in post #34.

Answer: 30 ft-lb, -78 ft-lb, and 48 ft-lb

CS
 
  • #40
stewartcs said:
No.

-5.57(7) is not correct...it should be, as stated numerous times above, -5.57(14). The 14 comes from 6 + 8 which is the distance between point A and reaction B.

CS
Ok sorry about that[tex]\Sigma{M_A} = 5(6) - 5.57(14) + 2(24) = .02[/tex]5(6) = 30 ft-lb
-5.57(14) = -78 ft-lb
2(24) = 48 ft-lb
---------------------
Sum = 0 ft-lb
 
Last edited:
  • #41
stewartcs said:
The answer is in post #34.

Answer: 30 ft-lb, -78 ft-lb, and 48 ft-lb

CS

I know but I need to show how I got them though, I need to know how to properly display the answer to the whole exercise.

Does that calculation I did in my previous post even part of it?, I don't see it asking for that right. It is just asking to calculate the Moments about A, I can just show how I get those and that's it right?.
 
Last edited:
  • #42
Dellis said:
Ok sorry about that

[tex]\Sigma{M_A} = 5(6) - 5.57(14) + 2(24) = 72.43 kips/ft [/tex]

I want you to multiply each term in this equation and right it down without adding them up and post the results.

CS
 
  • #43
Dellis said:
I know but I need to show how I got them though, I need to know how to properly display the answer to the whole exercise.

Does that calculation I did in my previous post even part of it?, I don't see it asking for that right, I can just show how I get those and that's it?.

Combine post #24 and #34 and that is the "work" that you should show.

CS
 
  • #44
Dellis said:
Ok sorry about that


[tex]\Sigma{M_A} = 5(6) - 5.57(14) + 2(24) = .02[/tex]


5(6) = 30 ft-lb
-5.57(14) = -78 ft-lb
2(24) = 48 ft-lb
---------------------
Sum = 0 ft-lb

The 0.02 is due to rounding errors...it should be 0.

CS
 
  • #45
stewartcs said:
The 0.02 is due to rounding errors...it should be 0.

CS

Ah ok, so other then that(which I will fix below) that is the end of this exercise?

[tex]\Sigma{M_A} = 5(6) - 5.57(14) + 2(24) = 0[/tex]5(6) = 30 ft-lb
-5.57(14) = -78 ft-lb
2(24) = 48 ft-lb
---------------------
Sum = 0 ft-lb
 
  • #46
Dellis said:
Ah ok, so other then that(which I will fix below) that is the end of this exercise?




[tex]\Sigma{M_A} = 5(6) - 5.57(14) + 2(24) = 0[/tex]


5(6) = 30 ft-lb
-5.57(14) = -78 ft-lb
2(24) = 48 ft-lb
---------------------
Sum = 0 ft-lb

Yes.

CS
 
  • #47
stewartcs said:
Yes.

CS

Thank you 1 million times, I really appreciate all the help and guidance.


As you seen on the forum I got a new thread, dealing with Free Body Diagram though and I got it done in a picture, just want to see what forces I missed, can you help me with that please?.
 

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