# Homework 27.A

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## 60 thoughts on “Homework 27.A”

1. Benjamin Lukas Holtmann says:

You can check your answer for the shear force by checking that your shear force at point E equals the force P.

1. Connor Filipiak says:

Agreed, this is a good way to check your work. Another way is that bending moment will return to zero at the end.

2. Stefan says:

Do we need to consider the moment around the application points of the forces, or around A and D?

1. Alexander Luis Yeverino says:

You should be sure to include Ax, Ay, and Dy

2. Sai Sanjit Ganti says:

Bending moment diagram requires you to calculate BM at each cross section along the length of the beam. So it is better to write your moment equation about a fixed point like A. Hope this helps.

Hello Stefan,

We sum the moments around either A or B to eliminate one of thee reaction forces and solve for the other one then by summing the forces in the y-direction we can solve for the other reaction force

4. Qinglan Wang says:

There are no moment at point A and D I think.

5. Chibuzor Vincent Nwaobi says:

Bending moment diagram requires you to calculate BM at each cross section along the length of the beam. So it is better to write your moment equation about a fixed point like A. Hope this helps.

1. Samantha Noelle Ferengul says:

I believe it is. I had there a force in the Y direction, and a force in the X direction, but no moment around A

Hello Lucas,

Yes A is a pin joint, but since no horizontal forces are acting on the beam, thus it has only a vertical reaction force, so it seems like its acting like a roller support

3. Elijah Marcum says:

I have it as a pin joint, however I think the x reaction is zero, since there are no forces in the x direction.

4. Yongchun Ni says:

I think A as a pin joint. Since there is no force in the X-direction, I think A has only a Y-direction force.

3. Kaylee says:

I also had the reaction forces at A in the X and Y direction, but no moment present.

1. Deepthi Kumar says:

I think at A there's no reaction force in the x-direction, only in the y-direction

2. Robert Christian Corridan says:

I believe you are correct that there is no moment at A because it is a pin joint; however, summing the forces in the x direction will only include Ax which must equal 0.

1. Kyle Robert Sikkema says:

Yes, no reaction in X direction due to the impending loads only projecting in the y direction. No side loads.

4. Hyunseo Lee says:

Should I draw a free body diagram with shear forces shown at B, D and E? Or just B and E?

1. Hayden James Lang says:

Hello Hyunseo Lee,
I am drawing a free body diagram for B,D, and E. They might only need two but I am drawing all three just in case.

I would also recommend drawing free body diagrams for B, D, and E.

5. Mitchell Lee Kisaberth says:

Whenever we make a cut, will it always include a shear moment?

1. Wei-ting Pan says:

Yes, no matter where you cut, always put a positive shear force and a positive moment on the place you cut.

1. Christopher John McBride says:

Wei-ting is right in that there will always be a positive shear force and a positive moment on the place you cut. Just remember that the side that you make your cut will influence the direction of the shear and moment. For example, if you make your cut and have the right face exposed, the shear force will be positive downward.

6. Lukas Karim Hessini says:

When making our V(x) and M(x) graphs, should keep them as open lines just on an xy plane or enclose the ends to the axies and shade in the area between the line and x-axis?

1. Ishita B Bhatt says:

Hello Lukas,
According to the examples done, the V(x) graph is enclosed with shading and the M(x) graph is just the lines, without shading.

7. Lauren says:

Is it assumed that the weight is negligible?

1. Ethan E Harbin says:

Yes, I believe that since the weight of the beam is not mentioned in the problem, we can assume that it is negligible.

2. Matthew Alan Harris says:

When solving the problem, I assumed that the weight of the beam is negligible, as it isn't specified anywhere in the problem.

3. Carolina Solis Blanco says:

Yes, I believe weight is negligible as it is not mentioned in the problem

1. Carolina Solis Blanco says:

Vx is the sheer force and Mx is the bending moment

1. Mitch Kamp says:

Yes, V represents shear force as a function of x, and M represents bending moment as a function of x also.

8. Khalaff says:

Where are there going to be moments present? Only at point E right?

1. Claire Qiao says:

Basically the moments occur at the ends of each segment which you can label as point P where the V force and Fn force are as well. It occurs at the ends where you cut off the segments. There shouldn't be a moment at Point E

9. Pedro Ornia Reyes says:

Do I need to do a moment about A or D to solve the problem?

1. Ronan Shieh Panicker says:

I believe when solving for your reaction forces, you use a moment about A in a global fbd so you're able to solve for the Dy reaction force. From there you can solve for the A reactions using sum of forces

10. kai says:

How do we know the distance our cut is from our points?

1. Mitch Kamp says:

You don't know, so you designate that distance as x. Therefore, the shear force and bending moment will both be functions of x. Additionally, x should always be measured from the same point for all cuts. That is, if you wanted to move left to right, you would have different x's for each segment, but they would all be measured from point A (for instance, for the second segment between B and D, x would be measured from A on the left to some point between B and D on the right. Therefore, d <= x <= 2d).

1. Mitch Kamp says:

Yes, all shear forces and bending moments are functions of x.

11. Aniket Singh says:

How many free body diagrams should we draw?

1. Mitch Kamp says:

You should have one for each segment in which the shear force and bending moment is different. So one for when 0 <=x<=d, a
second one for d <= x <= 2d, and a third one for 2d <= x <= 3d.

2. Lauren Nicole Slater says:

I had four in total, one for the entire system and and then three for each of the sections we are supposed to find.

1. Chun-wei says:

Yes, there will be reaction forces in x and y directions with moment at point A since it is a fixed support.

1. Chun-wei says:

Sorry, my mistake, I think there is no moment at point A.

2. June Kim says:

Just to clarify, there is no moment at point A because it is a pin joint as Chun-wei mentioned above.

12. Eric Hamilton Cockroft says:

Will the bending moment graph always return to zero if there is no reaction force at the end of the beam?

Correct, the bending moment graph will always return to zero. This is a good way to check if you did your calculations right.

13. Sarah Nicole Lavelle says:

When breaking up the sections of the beam, in the first section is there only the moment at the end of bending?

1. Eunice Song says:

Yes. There's that moment and Ay that are needed to solve for the bending moment.

14. Frederic Jeffrey Zahn says:

Why are the signs flipped for the V(x) calculation?

Will there be a moment about point A to calculate the bending moments?

1. Eunice Song says:

No. You only need Ay at point A, since there's no moment and Ax equals zero, to solve for the bending moments.

16. Brennan Stephen Birn says:

When Looking at Segment DE I assume we also need to account for the AD part in the moment and force equation right?

1. m says:

Yes, you need to include them to get the right answers

17. Hunter Thompson says:

How do we find the shear force given the load is only applied at one point and not a distributed load?

18. David Eldridge Knopp says:

Can we expect the line for M(x) to be continuous? I dont think V(x) has to be continuous.