Analysis of a system of bodies where all forces are in balance and there is no motion relative to a chosen reference frame.

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Determining the neutral axis of an I-shaped cross section with dissimilar materials

Determine the neutral axis of the I- shaped cross section with dissimilar materials. The top rectangle of the cross section is made out of aluminum and the second and third part are titanium ( these ...
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1answer
92 views

Newton's Third Law As Discussed in Den Hartog's Mechanics

A question, but some preliminaries in order to avoid answers involving concepts not yet introduced in the text I'm reading--Den Hartog's Mechanics. Near the very beginning of his book, Den Hartog ...
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1answer
55 views

Distribution forces

I've got two trees and between them is a rope. When someone about 100kg sits at the center of the rope, what are the forces on both parts of rope (to the left-hand side from the person and right-hand ...
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1answer
95 views

How does force transmit through a solid block?

If you take a solid block, say, a cube of side length $l$ with density $\rho$, you place it upon a solid floor, and you apply an external pressure of $p(x,y)$ on the upper face ($x$ and $y$ define a ...
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1answer
55 views

Seesaw Physics - Shipping Container House Problem

I'm currently building a house using shipping containers. One of the containers is in a cantilever position, sticking out from the base concrete structure like this: ...
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1answer
47 views

Lever Mechanical Advantage

In the attached image the force output of the plank is calculated to be the work done (FDf) divided by the height the block rises (Dw). So the force the plank applies on the block is (FDf)/(Dw). But ...
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1answer
30 views

Why can't we have more than 3 moment equations in equilibrium equations

Excuse me for a kind of stupid question but, In statics of a 3D rigid body, the equations to determine equilibrium are at most 6 (Fx Fy Fz Mx My Mz = 0) (not counting those from hinges and rollers). ...
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1answer
44 views

What does $\bar{x}_{\textrm{el}}$ represent?

In the context of centroids and moments, what do $\bar{x}_{\textrm{el}}$ and $\bar{y}_{\textrm{el}}$ represent? For example: $$\bar{x}L = \int \bar{x}_{\textrm{el}}dL$$ Some references that use ...
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1answer
591 views

How do I know which force to use in moments calculation?

I'm working on some Statics problem, with the method of joints, etc and for all of them, we use sum of moments = 0. However, I'm very confused about which forces I should use to find the sum of ...
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0answers
873 views

Shape of a string/chain/cable/rope/wire?

The height of a string in a gravitational field in 2-dimensions is bounded by $h(x_0)=h(x_l)=0$ (nails in the wall) and also $\int_0^l ds= l$. ($h(0)=h(l)=0$, if you take $h$ as a function of arc ...
3
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0answers
162 views

Obtaining point of application of Ground Reaction Force with use of a hyperstatic load-cell array platform

I'm looking for the theory of an experiment that is giving me a hard time to perform. I have an instrument composed of a rigid horizontal square plate rigidly supported under each corner by a ...
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0answers
2k views

Forces and torques about the CENTER OF MASS of a physical pendulum

I'm currently stumped by the following situation. Say we've got a rectangular physical pendulum (think ruler with a hole-punch at one end). It's trivial to analyze the motion of the pendulum with the ...
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0answers
153 views

Moment line of action

I am having trouble understanding a moment's line of action. Lets say we have door hinge of $L$ length and push down on it with $X$ force. The moment at the begin $(O)$ of the hinge would then be ...
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0answers
34 views

Dropping vertices of an overdetermined statics system graph

In statics, the problem of determining the tensions of K cables that connect a structure made of N points and keep all points in static equilibrium implies $ND$ systems of equations, where $D$ is the ...
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0answers
393 views

Mechanics of Materials (pressure and temperature)

A solid right cylinder of rock core is surrounded by four rods made of mild steel (all-thread rods). The rods are placed equidistantly around the core in a square formation. The tops and bottoms of ...
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0answers
22 views

$16~\rm N/mm^2$ flexural strength

This question more relates to construction and architecture but I am sure it will not be the problem to ask and get a good answer here. If we have declared flexural strength of concrete of 16 N/mm2, ...
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0answers
18 views

Determine the point at which moment vector is zero on a 3D body

I have information about total force and moment on a body for three points, whose coordinates I know. From this information I would like to determine the point at which moment would be zero. ...
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0answers
26 views

Shear flow in J section type beam

What does the distribution of shear flow look like in a J section type beam. I'm only interested in a qualitative picture of it. I'm not interested in the calculations themselves. It is the top of the ...
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0answers
88 views

Statics: Cable with distributed loads. What am I doing wrong?

This is the problem: It says: If the maximum value for the ABCD cable's tension is 15 kN, determine: a) $h_b$ b) $h_c$ My development was: 1) Whole body (ABCD). Sum of momentums in D equals ...
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0answers
47 views

When a force applies to a rigid body at point, then does every part of the body experience the same kind of force?

Suppose that a rigid body is static under the action of several forces that are applied at different part of the body. Then is it true that if one divides the body into small pieces, then each piece ...
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0answers
42 views

How do I minimize the the stress created by fore-aft forces?

My friends and I are designing a bench press spotter. Essentially, when the user needs help lifting the barbell due to muscle fatigue, an arm on each side of the user raises to provide assistance. ...
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515 views

How to solve fixed-fixed beam with finite difference method?

What equations to use on this system to form a matrix $A$ with dimensions $[n,n]$ and load vector $q$ with dimension $[n]$ ? I am trying to get vertical displacement $w$. $$w = A^{-1}\times q$$ ...