Homework Help: Equilibrium state

1. Oct 25, 2015

Ivan Antunovic

• Member advised to use the homework template!
Problems stated in attached pictures.So could someone explain me what am I doing wrong here this is solution for the example a) .
I tried it twice and I am getting wrong results.

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2. Oct 25, 2015

Ivan Antunovic

Sorry for the 2nd picture in my first post,hope it's not rotated this time.

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3. Oct 26, 2015

haruspex

To get the given answers in the first question, you would need to use a=4 and b=6, or something equivalent.

4. Oct 26, 2015

Ivan Antunovic

First of all thank you for replay.

Thank you man so much.I was really confused whole Sunday trying to figure out if I was doing something wrong. Now I've gotten correct answers for both cases a) ,b) and c).

I have one more question.I took intuitively an angle between Forces Fb and Fby to be 45 degrees but I am trying to figure it out mathematically.

5. Oct 26, 2015

Ivan Antunovic

6. Oct 26, 2015

haruspex

I assume this is in relation to c.
The question as given is not clear enough to obtain an answer. It would be better if it showed B as a flat plane at 45 degrees, stated to be frictionless. In that case you would deduce that the normal force is also at 45 degrees to the vertical.

Last edited by a moderator: May 7, 2017
7. Oct 26, 2015

Ivan Antunovic

Yes I was talking about c example.
There is actually no way to find Fa x and Fbx unless assuming that the angle is 45 degrees,since both of those forces go through point A and B so their torque is zero at those points.

8. Oct 26, 2015

Ivan Antunovic

I have one more question if you could check if I was doing everything fine in this task.Text goes:

The tops of an equilateral triangular plate , where the side length is a = 100 mm and where forces are operating which are F1 = F2 = F3 = 2 kN and torque M = 0.1 kNm .
Thickness and weight plates ignore . Reduce the set and force a default torque M at point A.

http://postimage.org/ [Broken]

http://postimage.org/app.php [Broken]

Last edited by a moderator: May 7, 2017
9. Oct 26, 2015

haruspex

I take it from your diagram that the three forces are all in the plane of the plate and act as shown. But I don't understand the last sentence. What does it mean? Is that the exact wording?

10. Oct 27, 2015

Ivan Antunovic

I tried to translate it well from my language,but google translate failed this time so I will try to explainit,it is required to translate all forces and given torque at point A

11. Oct 27, 2015

haruspex

The three forces are each directed along a side of the triangle from their points of application, yes? Rather than leap into converting each force into X and Y components, think about the line of action of F3 and what that implies for its moment about A.

By the way, your images are not easy to read. The writing is a little faint, and I see your shadow on them. It is much easier for others if you take the trouble to type your working in. In particular, it makes it much easier to quote and draw attention to specific lines of algebra. The ability to upload images is really for textbook extracts and diagrams.