Questions tagged [statics]

Statics is branch of engineering concerned with the analysis of forces and moments on physical systems in static equilibrium.

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6
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3answers
2k views

Mathematical representation of hinge and pin connection

Following on from this answer, I am reading about the difference between hinge and pin connections here, and I don't quite understand about it. I think I would need to see the mathematical ...
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1answer
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Is pin column-beam joint always have less moment, more deflection compared to fixed joint?

I am referring to the answer here: It seems that on a simple structure (The diagrams on the left the images below have fully-fixed connections, while on the right the columns are pinned connections ...
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2answers
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Does thickness impact resolving loads for an inclined beam?

I have a 3 m x 1 m x 1 m cuboid weighing approximately 10,000 kg. I am trying to resolve the vertical forces that will support the cuboid if the cuboid must rest at a 45 degree angle. Which of the ...
6
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1answer
448 views

Fragmentation of a curved cantilever beam under compression

Suppose we have a curved beam of a rectangular cross-section $A$, Young's modulus $E$, and a constant radius of curvature $R$. We now expose the beam to a vertical point load of magnitude $P$ at its ...
3
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2answers
290 views

Replacing a straight rigid link by a curved rigid link

Suppose we have a horizontal rigid bar hinged at one end to the wall. An inclined straight link hinged at one end to the same wall, is pinned to the rigid bar at its center. A load P is acting at the ...
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2answers
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Does an external force at a joint between two members act on one member or on both?

I am trying to find the internal forces in the member at point G in the following illustration: My answer is different from the solution in the textbook and I think it has to do with how I'm looking ...
5
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1answer
463 views

How can I translate a pressure boundary condition to a velocity boundary condition for incompressible, viscous flow?

I have been working with an old code for modeling incompressible, 2D viscous flow out of a tank to understand a chemical process. There isn't much documentation and I'm not a fluid dynamicist, so I ...
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0answers
540 views

Incompressible 2D pressure-driven flow: for Navier-Stokes equations in nondimensional form, how should I express pressure boundary conditions?

*I have updated this question. I'm using two codes for modeling incompressible, two-dimensional flow out of a tank. My fluid dynamics experience is pretty basic; I'm using the codes to understand a ...
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2answers
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Determine the moment of inertia of a filled circular sector

Does anyone know how to determine the moment of inertia of the filled circular sector shown below? Apparently I have to use $dA=r\ d\theta\ dr$, $y= r\sin(\theta)$ and end up getting $I_x=\frac{r^4}{...
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1answer
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Where did I go wrong conceptually when attempting to calculate the maximum force on a truss at a given joint?

In the problem statement below, the question states to find the maximum load $\vec{P}$ that the truss can support. My method of approach was: Draw a FBD for the entire structure. Generally I would ...
6
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1answer
492 views

Differential equation of the vertical displacement of a cable

Given a cable (totally flexible) fixed at both ends, subjected to a vertical force $f(x)$ in his plane, with variable area $A(x)$, and variable elasticity $E(x)$ I want to find the differential ...
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2answers
981 views

Maximum deflection of a beam with both ends fixed and distributed load

I'm designing a part, and I'm trying to figure out what distance a slot should be from the bottom of the part. For simplicity in analysis, I'm approximating the region between the bottom of the slot ...
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2answers
4k views

Horizontal and vertical forces on supports

Calculate the horizontal and vertical components of the reactions at the supports. I found the horizontal force for the pin by adding the forces to 0 and I know I can find the vertical reaction of ...
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1answer
193 views

Reduction of a simple distributed loading (correct question)

I am not yet at the chapter of equations of equilibrium, plus it says the couple moment is not 0, so I assume it just about the loadings and not including the reactive forces and reactive moment. So ...
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1answer
1k views

Reduction of a simple distributed loading

This is the question, but with me 6 kN/m is 4 kN/m and 2 kN/m is 2.5 kN/m. And the length is not 4 but 9 metres. I am not yet at the chapter of equations of equilibrium, plus it says the couple ...
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2answers
2k views

Determining the magnitude and coordinate angles of a resultant couple

Here is the exercise that I just can't seem to figure out. The answer should be 71.9 Nm with coordinate angles 44.2, 131 and 103. I know that the couple moments caused by the forces $F_1$, $F_2$, and ...
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3answers
6k views

Why do we assume the moment is zero when analyzing a simply supported beam?

When calculating the reactions of a simply supported beam under any type of loading we assume that the moment about the reaction points is zero. What if our assumption is wrong and in actual practice ...
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1answer
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Find Acceleration Of A Buoyancy Force Of A Balloon In U.S. Customary Units (1-49E)

The problem in my text (Thermodynamics An Engineering Approach, Cengel & Boles, 2nd Ed.) is stated as follows: Balloons are often filled with helium gas because it weighs only about one-seventh ...
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2answers
1k views

Statics and Structural Analysis: Determinacy in beams/frames

I have a question about the methods to decide whether a beam/frame is determinate or indeterminate. Typically you can count the number of reaction forces and compare them to the number of elements to ...
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1answer
125 views

What engineering topic builds upon the concepts of basic statics?

I'm interested in learning what I might call "advanced statics" but am not sure what concepts this would include in engineering parlance. Would it actually be called "matrix structural analysis"?
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2answers
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Best angle and length for a diagonal wood support for a pull-up bar

I want to construct a freestanding pull-up bar like the one described here. But I was wondering what would be the best angle for a diagonal support considering that the things I care are: That it ...
7
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1answer
2k views

Calculate effort to raise hinged lever with distributed load

My father-in-law would like to install a hinged stair system in his garage that allows him comfortable access to his attic space. He wants the stairs to swing up flush with the ceiling when not in ...
2
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1answer
1k views

Drawing Bending Moment Diagrams

How do I know when to use an upward or a downward curve when I'm drawing a bending moment diagram for a uniformly-distributed load (UDL) and what's the most reliable way of identifying the maximum ...
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1answer
2k views

How to calculate strain from maximum bending moment and stress?

How can I calculate the strain in a simply supported beam from having the maximum bending moment (25kNm) and the maximum bending stress (45MPa)?
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1answer
701 views

Frame/truss problem with sliding joint

I'm supposed to be finding the reaction forces first but from the FBD of the entire truss where am I supposed to start. If I take the moment at A then I get 3 unknowns at Bx Dy and Dx. If I get the ...
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1answer
1k views

Loaded Truss problem

Hi, I'm having some problems with this truss question that I have in my homework. So far this is my solutions. I worked out my solutions to the reaction forces but don't know if they're correct. The ...
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2answers
4k views

How to calculate the forces on members of a frame, due to a distributed pressure load?

I am trying to calculate the force sustained on the three labelled members of this frame (Members 1, 2 & 3). The frame will experience a uniform pressure of 1000 kPa in the area enclosed by the ...
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1answer
55 views

The Equation of a buckled card

When a rectangular piece of plastic (say a credit card) experiences an increasing compression force, the plastic eventually buckles. Is it possible to find the equation of the plastic's cross section ...
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2answers
1k views

Why is there a moment at the cross section end when you cut a body?

I just started mechanics of materials, and it seems that my knowledge from statics has gotten rusty over the summer. But there was a new concept introduced in the first example problem today. There ...
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1answer
1k views

Calculating automotive suspension wishbone loads by considering the structure as a 3D Truss

I am trying to calculate the loads in the suspension components of a typical car double wishbone setup. I have found a thread on the www.fsae.com forum, which seems to be exactly the kind of thing I ...
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1answer
1k views

How to analyze the free body diagram of a pair of scissors? [closed]

Is this how it works? The fingers generate moment. The load generates moment. Finger moment > load moment, so the load is cut. How do I use an equation to identify the most vulnerable point of the ...
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2answers
32k views

How to deal with a point force acting right on the hinge of a beam?

I have been attempting to solve a question where there is a point force acting on the hinge of a beam. Here is the problem: I am not sure how to deal with the 2 kN point force at $C$ ($C$ and $E$ are ...
3
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1answer
4k views

Drawing the shear and bending moment diagram of a 2D rigid frame [closed]

I am taking a civil engineering course that we are constantly asked to tackle questions that are not really covered in the course. I have been looking for suitable reference materials but with no ...
2
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3answers
895 views

How to describe the rotation of opposite ends of a body due to an applied moment

Summary A short way to phrase this question is: Shear describes the translation of one part of a body relative to another given an applied force. What is the equivalent rotational term? That is, ...
4
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0answers
125 views

Calculating a pull force between two pieces of plastic

I have an HDPE pin, 2 mm high, 2 mm diameter, that I impress into a flat plaque of hot HDPE. It is not hot enough to melt the pin, but still hot enough that the material will shrink 4% in 24 hours. ...
4
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1answer
18k views

What angle - for a strut - provides the greatest vertical strength/support for a cantilever?

I want to affix a cantilever to wall. I will support the other end of the cantilever with a strut made of wood, that attaches to some point on the wall below the cantilever, as shown in this sketch (...
4
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4answers
3k views

How to calculate a tripod table's stability?

I have designed a circular, 800 mm (31.5") diameter tripod table. The top is made of stone and weighs 40 kg (88 lbs). The height of the table is 750 mm (29.5"). There is a central column with tripod ...
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3answers
3k views

Does the length of a beam change upon deflection?

I have made a Python program in which I have computed the deflection of a beam. I am plotting the deflected beam and am now asked to show the length of the beam. If the beam is not deflected, it is ...
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2answers
3k views

Beam with constant load distribution on three supports - force distribution to supports

I have following example (the question is at the bottom): The load distribution $q$ is constant. I add condition of zero bend in center of the beam, $w_B = 0$, and the assumption $F_{RA} = F_{RC}$. ...
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2answers
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How to solve an overconstrained static free body diagram?

How does Force Effect https://forceeffect.autodesk.com do it? Given a 10m long bar angled as the hypotenuse of a 3, 4, 5 triangle with an xy pin constraint a (0,0), another xy constraint at (4,3), ...
3
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1answer
564 views

How do I determine the reactions at the base of a tethered T-frame?

I received a tricky bonus question today in my engineering class: I've begun by equating all moments and forces to zero, about an arbitrary point, which I labeled at $C$. Finally, I attempted to ...
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5answers
17k views

How to calculate lever force when lever has uniformed distributed load?

We have a simple class 1 lever: $$\begin {array}{c} \text {5,000 kg} \\ \downarrow \, \downarrow \, \downarrow \, \downarrow \, \downarrow \, \downarrow \, \downarrow \, \downarrow \, \downarrow \, \...
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1answer
3k views

Is the Qmax of an T-Beam equal if calculated both above and below the neutral plane?

I was doing a question involving a T-Beam question wrong since I was selecting the wrong area to use for $Q_{max}$ when trying to maximise the shear stress. $$\large{\tau}= \frac{VQ}{It}$$ A friend ...
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1answer
4k views

What is the benefit of additional planetary gears?

A planetary gear is a gear that rotates not around an axle but around another gear known as a sun gear, or star gear. I have designed prototype systems in the past that used a single planetary gear ...
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4answers
6k views

How do I calculate the forces on a desk and its legs?

I have a design for a desk, and I'd like to not just guess at how strong it'll be, but I can't find an explanation on how to figure out all the forces involved that doesn't assume I already know a lot ...

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