Questions tagged [moments]

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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
723 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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2answers
1k 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
87 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
622 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
307 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
3k 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
183 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
299 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
4k 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
2k 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
580 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
92 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
224 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
491 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
3k 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}{...

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