Questions tagged [moments]

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2nd Moment of Area of a ring

This is my first question here. I am having trouble finding the 2nd moment of area of a ring with a thickness 't' and radius 'r'. I seem to be a factor of 2 out. What I do is I consider an area like ...
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3answers
40 views

Is there a 6th equilibrium equation for a static beam?

For a scholarship exam I'm taking, it takes simple enough ideas and then messes with them in crazy ways. In this question four of the equilibrium equations I'd use to solve this are linearly dependent....
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Finding Tension in cable in 3D Equilibrium

In a typical 3D Equilibrium problem. Assume you have two cables points supporting a mass. The two cables are K distance above origin and form a quadratic triangle with the mass which is a the same ...
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2answers
62 views

Resolving moments and forces

The calculations for a design I am doing are making me go round in circles. I have simulated the design but I cannot seem to resolve this mathematically and it is really bugging me! Below is an ...
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1answer
38 views

Is there a moment at a point between two connected sliders, when one is subjected to a force? (schematic shown)

Background: I'm designing a machine that uses an actuator to push an object. The connecting component may not take certain bending forces, therefore I'm trying to evaluate the system with a free body ...
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1answer
35 views

Sign convention-moment

I am having a hard time taking care of signs. Whether we’ve made the cut at right or at left. Whether should we make the rotation according to axis x, y or z. In this case, they assumed that P was ...
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2answers
464 views

The internal normal force, shear force and moment

How do I determine the internal normal force, shear force and moment at the point C? $V_c = 0$, $N_c = 0$ and $M_c=3.75 kN/m$ I have already done this: Where is the problem?
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2answers
384 views

Shear force and bending moment for continuous span

It's given that L1 = 5m, L2 and L3= 7.5m, w = 8.9kN/m , I am asked to find the bending moment using these coefficient.. Prior to this , i need to have the value of shear force first.Shear force = ...
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1answer
252 views

A way to calculate the magnitude of the moment

In my engineering textbook, I didnt understand the example given to explain the magnitude of the moment. It asks to calculate the magnitude of the moment about the base point O of the 600-N force in ...
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0answers
29 views

Most efficient way for finding the rotation angles after moment distribution (Cross method)?

First of all, I have taken a look at the Grinter's method, which is similar to Cross, but balancing angles instead of moments. My question assumes that we are using the Cross method, and not the ...
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1answer
45 views

How to solve for moment with uniform distributed load

How do we get the moment when there's a distributed load? For example, the picture below has 9[(60)(18)]. I get that 60 is the distributed load and 18 is the total length of the load, my question is ...
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1answer
79 views

Shear force and bending diagram un-uniformly distributed load

I already got great help on this topic, but I'd like to make sure that I get it. For example, take a beam of length 6 meters, left side fixed support and right side rolled support. There is a load of ...
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3answers
1k views

Transfering moment through internal hinge

My professor says, the internal hinge can not transfer moment: But can we calculate $\Sigma M_A=0$ for whole beam ( without cutting it or something) this way?: $\Sigma M_A=0 ===\Rightarrow M_A+(D_y ...
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0answers
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Shift of joint in kinematically indeterminate system

Given ist the following system: $$EI=100000\frac{\text{kN}}{\text{m}^2}$$ $$EA\to \infty$$ I'm suppossed to find the horizontal and vertical shift of joint g. My first approach was to use the ...
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1answer
122 views

Skewing of joints using virtual work

Given ist the following framework: $$E=210 \frac{\text{kN}}{\text{mm}^2}$$ $$ EA \to \infty $$ $$ I_1 = 80000\text{cm}^4 $$ $$ \frac{I_1}{I_2} = \frac{3}{4} $$ $$ I_3=I_1 $$ Using the principle of ...
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3answers
495 views

Calculating moment of inertia for a hollow discontinuous circle?

This is a pretty simple problem, but I'm just not sure how to go about it. I want to find the moment of inertia of a discontinuous hollow circle. But since the shape is so irregular, I'm not sure how ...
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1answer
2k views

Transfer of moments in beams with internal hinges

We have a beam with 1 internal hinge just like the picture. We know the internal hinge can not transfer moments between AB and BD. We know the 30 kN force makes some moments on BD & AB. If B (...
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0answers
39 views

Pin, Slot, and Spring Equilibrium

I am checking to see if this is done correctly, the slot is a little confusing for me. B is a pin in a slot, solve for the spring constant (k) so the 50 lb force applied does not move pin B Solving ...
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3answers
751 views

is bending moment on roller supports at beams zero?

isn't the bending moment supposed to be zero on roller supports at beams? then why isn't it zero here in this picture at x=2?
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3answers
452 views

Second Moment of Area for slanted triangle?

Consider this triangle with its centroid at $C$: Then this is how I believe we can calculate the Second Moment of Area along the $x_{C}$ and $y_{C}$ axis: $$\begin{align} I_{xc} &= \frac{bh^3}{...
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1answer
77 views

Plastic Hinge by Skyciv

Is it possible to determine plastic hinge location of a frame in SkyCiv? Is it also possible determine moment -curvature relationship curve in SkyCiv? If yes, how?
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1answer
1k views

Sheet Metal Bending: stuck on calculating the minimum radius required

I'm used to calculate the minimum radius required for bending operations on both aluminum and steel sheets, given the following parameters: https://imgur.com/a/7akHC Problem statement: For a sheet ...
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4answers
128 views

Moment and Torque at a Single Point

As far as I know, moments/torques occur when forces applied are not in line. However, I often see moments/torques being applied at a single point in free body diagrams. How can moment/torque be ...
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2answers
131 views

Finding the force in a cable of a rigid system

QUESTION (see attached image file): I got stuck when trying to find tension for part A; see my working below. and help me solve.
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1answer
984 views

Determine the reactions at A and C, knowing that α = 30º [closed]

QUESTION(see image attached): Really need help here can someone help me show how we get the solution as shown in the image file attached above. okay since I was asked by one of the users ...
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1answer
245 views

Is radius of gyration same for both types of moment of inertia?

We know that moment of inertia is commonly known as second moment of area. Which is $\int_{}{} y^2 dA$. However there another moment of inertia called as mass moment of inertia given by $\int_{}{} r^...
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1answer
424 views

polar moment of inertia for compound shape

I have a shape that I'd like to calculate the polar moment of inertia for: the diameter is 600mm; the hexagon in the middle sides are 70mm each; the holes around the hexagon are 130mm from the center ...
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1answer
682 views

Maximum torsion shear stress in cylinder

I am trying to figure out am I doing this calculation correctly. To get the maximum shear stress for a solid cylindrical pipe I need two formulas: Moment of inertia = pi/2*r^4 Not sure what this ...
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2answers
79 views

moment of inertia forces and torque

I did some calculations to find out the moment of inertia and physical qualities of some metal. I am using typical medium carbon steel. I'll use a density of 7.8 g/m^3 until I get better numbers. ...
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2answers
313 views

Moment of force or torque [closed]

Is the moment of force taken in a clockwise and anticlockwise fashion? Why then do we curl our fingers and check it?Explain the equivalence or similarity between the two.
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2answers
187 views

Moments of inertia, rods mechanism

I need some assistance understanding moments of inertia. I am doing some review for an upcoming exam, however I am slightly stumped by this question. I have already tried googling "moments of inertia" ...
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2answers
1k views

Fluid mechanics- Force required to keep the gate closed

I have to answer the following question which is (image shown above) "what is the force to keep the rectangular gate closed? in N/M" This is all the information I have to solve the question. I ...
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1answer
153 views

Structural mechanics - computing bending moment

I am having difficulties trying to work out one problem. I've attached a picture explaining the situation - the task is to determine internal forces in C but the bending moment M(x) doesn't seem to ...
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1answer
249 views

What are the principles (if there are any) behind the conservation of bending moment in frame analysis?

I notice from this question that the moments at joint connection are somehow "conserved", or being "transferred" from one element to the others. In other words, there are no "missing moment". Note ...
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2answers
3k views

Force required to rotate an object on a plane - moment of inertia?

I have a rectangular shape with uniform mass, approx 6m x 1m. It rotates around an axis in the centre of its width but 1m from one end. The axis has some friction but this is not known. What I need ...
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1answer
1k views

Calculating the moments due to reaction forces on a bent beam

I am trying to solve the following problem: EXAMPLE 2.10 Determine the reactions on the beam in Fig. 2–30a. Assume $B$ is a pin and the support at $B$ is a roller (smooth surface). ...
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2answers
384 views

Flexural modulus for a beam fixed at one end

For a beam supported at both ends with a mass in the middle, the flexural modulus is given by: $$E_b = \frac{F L^3}{48I d}$$ with I as the area moment $$I = \frac{1}{12}wh^3$$ How does the ...
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1answer
69 views

Shear Stress / Flexure Stress Formulas / Tables

Is there something similar to the Section Modulus in the Flexure Formula $$\rho_{max} = \dfrac{M_{max}}{S}$$ where $S = \dfrac{I}{c}$ for shear stress formula? So in $$\tau_{max} = \dfrac{VQ}{IT}$$...
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3answers
141 views

Different measured strain in beam experiencing pure bending

I have a beam experiencing a pure bending moment. The setup is similar to this image from these lecture notes (with different values). Using the flexure formula, we can determine that the stress (and ...
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2answers
426 views

Buckling of a cantilever with midway support

I'm trying to understand the implications for buckling and column sizing in the drawings below. A 3000mm 120x60 RHS steel column supports a 350mm horizontal steel beam. The column base and right side ...
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2answers
1k views

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}{...