Analysis of a system of bodies where all forces are in balance and there is no motion relative to a chosen reference frame.
Questions tagged [statics]
625 questions
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A simple (?) problem of static equilibrium
A question on the site made me consider this simple problem, that unexpectedly seems to be indeterminate.
Consider a perfectly rigid, homogeneous bridge of mass $m$ with three pillars, one placed under the center of mass (2) and the other two at…
valerio
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Statics question: When do I need to find support reactions?
We're finding forces (and whether they're in tension or compression) using the Method of Joints and Method of Sections. I don't understand why sometimes it's necessary to find the support reactions, but sometimes it's not. Please help. Thank you!
ChrisC70
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3 answers
How to interpret explicit moments in beams?
Consider the beam in the picture above. There are several forces that cause moments around all points in the beams. But there is also one "explicit" moment: 20kNm.
How do I interpret these kinds of moments? Here the arrow goes around the point 2m…
S. Rotos
- 903
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In this video what do we include theta when determining sum of components?
In this video here at 4:21, why do we not include sin Θ when calculating the y components of the ladder and the man on the ladder?
The equation written is just
0=-mg-mg+N
Should it not be
0=-mgsinΘ-mgsinΘ+N
Also eventually he used sin Θ for…
Harry Iguana
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What is the correct intuition behind Varignon's Second Theorem? (See the example in the details.)
Consider, say, a rigid 2-D square sheet, of uniform mass density, initially occupying the square:
$$-2 \leq x_1, \ \ x_2 \leq 2$$ in the $x_1 x_2$-plane. The plane is a frictionless table, on which the sheet lies.
For simplicity, consider applying a…
avs
- 111
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1 answer
Geometry of deformation of Axial members connected to a rotating rigid element
On axial members connected to a rotating rigid element,
we have the following relationship
$$\frac{-\delta_1}{a}=\frac{\delta_2}{b},$$
which is based on the concept of similar triangles.
In the relationship, what is $a$ and $b$?
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vote
1 answer
Center of mass of a rotating object
I read that if the left block moves up by $dx$ then the center of mass of the rotating object moves down by a vertical length of $\frac{1}{2}dx\sin(\phi)$ but I thought it would move down by $dx\sin(\phi)$ as doesn’t the disk rotate down a length…
Gary Song
- 329
0
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1 answer
Why is this force completely vertical?
I have the following system, which is in equilibrium:
It's a bar that can pivot around A, and is held in place by a string at B
I'm supposed to find the force applied to the bar at the pivot. I assumed that said force would have a component on the…
0
votes
1 answer
Can the equivalent point weight extend beyond the body on which it acts?
If the x location of the centroid equals (moment about O)/(equivalent point weight) and there are forces acting above and below the given body, couldn't the value of the x coordinate potentially extend beyond the body?
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2 answers
Why is the horizontal component of the reaction force at one of the hinges (which has a rounded bottom) neglected?
In the textbook "Engineering Mechanics: Statics (7th edition)" by James L. Meriam and L. G. Kraige, Chapter 3: Equilibrium, in the section titled: "Examples of Free Body Diagrams", I found an example which seemed quite confusing to me.
The force…
user139621
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votes
1 answer
Force couple simplification
How is it possible to add all the force components to find resultant when forces are acting at different points on the body?
0
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1 answer
Maximum Load of a Crane before Car will Tip
Imagine a car with a crane.
In scenario 1, the tension on the crane cable by the load points straight down, ie, perpendicular to the ground.
In scenario 2, the tension on the crane cable by the load points 30 degrees outward from a line…
Akitirija
- 121
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votes
1 answer
Distortion of non-circular cross sections upon torsion
True or false? Non-circular cross sections can be non-planar when torsion is applied. This was on a quiz today and I wasn't sure of the answer. I guessed true by intuition, but does anyone have a better answer/justification?
John doore
- 23
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Why don't underground tunnels collapse on themselves?
I understand that underground tunnels don't collapse because the forces acting on it must be in equilibrium but I don't know which forces are present and I don't know how they are built.
Marcio
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Static analysis of rigid bodies in 3D
How to calculate torque due to gravity of a 3D linkage mechanism? I am performing a static analysis of a Baxter Robot arm. How to calculate the torques at each of the joints ?
Riddhi
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