Questions tagged [statics]

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

Filter by
Sorted by
Tagged with
18 votes
5 answers
5k views

Why are screw holes in most of the door hinges in zigzag orientation?

What advantage does it provide? Explaining with a figure would be helpful. I tried to draw a free body diagram and equated the sum of force and moments to zero, but still was not able to find out.
Qwerty's user avatar
  • 181
18 votes
4 answers
6k views

How should I position two shelf supports for the best distribution of load?

I'd like to mount a shelf on the wall. I have two shelf supports to do so, like this: Relative to the shelf, where do I place the (blue) supports to achieve the best distribution of load?
Nico Schlömer's user avatar
13 votes
5 answers
19k 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 \, \...
Van's user avatar
  • 241
12 votes
7 answers
7k views

Why does a gear have extra holes?

In a gear you normally have a center hole for the shaft to be put into. Why do some gears have holes surrounding that center hole? Is it for weight reasons? Does it add stability? Is it so you can add ...
Mat NX's user avatar
  • 265
12 votes
4 answers
10k 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 ...
mordac's user avatar
  • 121
10 votes
1 answer
2k views

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 ...
Hunter's user avatar
  • 203
10 votes
2 answers
36k 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 ...
saldtch's user avatar
  • 149
9 votes
1 answer
5k 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 ...
Sam Weston's user avatar
8 votes
3 answers
2k 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 ...
tempestwing0101's user avatar
8 votes
5 answers
2k views

Height limits of brick and mortar tower?

What are the factors limiting the height of a "tower" made of typical fired brick and mortar? By "tower", I mean a structure whos point is to be tall, and can support a human standing on or near its ...
Olin Lathrop's user avatar
  • 11.4k
8 votes
2 answers
554 views

Moment equation from dynamics differs with equations from physics & statics. Where did I go wrong?

In my dynamics class, we're being asked to solve the following problem: My Attempt: Since I'm given the initial velocity, final velocity, and distance, I solved for the acceleration of the plane ...
Chris Forsyth's user avatar
8 votes
0 answers
656 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 ...
Ant's user avatar
  • 245
7 votes
1 answer
3k 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 ...
alfreema's user avatar
  • 353
6 votes
3 answers
3k 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 ...
Graviton's user avatar
  • 1,264
6 votes
1 answer
566 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 ...
David's user avatar
  • 61
6 votes
1 answer
654 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 ...
Msegade's user avatar
  • 193
5 votes
3 answers
4k 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 ...
Jamgreen's user avatar
  • 221
5 votes
2 answers
5k 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}{...
strateeg32's user avatar
5 votes
3 answers
4k 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?
niosha afsharikia's user avatar
5 votes
4 answers
5k views

Why do we ignore horizontal reactions at roller supports?

When talking about roller supports in a statics problem, we say that the roller prevents only the vertical translation of the beam, but not the rotation or the horizontal translation of it. So there ...
Eman.suradi's user avatar
5 votes
1 answer
381 views

How to draw a shear force diagram when two forces are acting at the same point

I am working on this question on my statics assignment: Approximately at point B there are two forces, 20kN and 50kN.So far, I have only calculated global equilibrium and got the following values: $...
AugieJavax98's user avatar
5 votes
1 answer
17k views

Shear Force Diagram of a Simply Supported Beam with triangular load distribution

I've been attempting this fundamental shear force diagram problem for several days, but can't seem to get the correct result. I'm trying to calculate the shear force diagram in terms of $x$, but I'm ...
AVelj's user avatar
  • 153
5 votes
1 answer
680 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 ...
Ant's user avatar
  • 245
4 votes
1 answer
4k views

What is the advantage of statically indeterminate structures?

Most of the real life structures are statically indeterminate. What is the benefit of designing a statically indeterminate structure instead of a statically determinate one? I don't mean only beams ...
veronika's user avatar
  • 223
4 votes
2 answers
2k views

Given the tensile strength of a rod, how do you calculate the max weight that can be hung from it?

Given a 3.25" long, 0.125" diameter rubber rod with tensile strength 1200 psi supported on both ends, how much weight can you hung from the middle of it without breaking it? (This is not homework I am ...
chx's user avatar
  • 143
4 votes
2 answers
23k 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 (...
Kreeverp's user avatar
  • 143
4 votes
1 answer
25k views

How much weight can an aluminum tube beam support?

I'm building a set of monkey bars for my kids and want to use aluminum tubing (6061 T6) for the rungs. The tubes will be 3 feet long and 1 inch outside diameter. Supported on both ends with a circular ...
Egor's user avatar
  • 143
4 votes
4 answers
4k 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 ...
rupert's user avatar
  • 41
4 votes
2 answers
3k views

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), ...
SpeedCoder5's user avatar
4 votes
2 answers
2k 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 ...
Grady F. Mathews Iv's user avatar
4 votes
1 answer
5k 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 ...
saldtch's user avatar
  • 149
4 votes
1 answer
182 views

3D construction [closed]

Can someone please tell you what to start with to construct a Kids Bike Trailer as 3D. It should select material and geometry. I think I should start sketching with forces (children's weight) and ...
Zouhir Bensebban's user avatar
4 votes
2 answers
6k views

How does a pulley (with friction) satisfy equilibrium?

In the picture shown : Suppose that there is a man applying a force $F$ in order to support the box using a cord that wraps over a frictionless pulley (the system is in equilibrium and nothing is ...
Eman.suradi's user avatar
4 votes
1 answer
933 views

Calculate max deceleration without front wheel slipping (bicycle)

I am trying to calculate the maximum braking force/deceleration for a bicycle. Note: the question assumes only the front brake is used Free body diagram: Typo: in the image above, "$F_{a,\ max(...
Maarten -Monica for president's user avatar
4 votes
1 answer
152 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 ...
Skydiver's user avatar
  • 245
4 votes
1 answer
226 views

Dimension of the unidirectional mechanical clutch

This is a problem from the book Engineering Mechanics Statics vol-1 by Meriam Kraige. The elements of a unidirectional mechanical clutch are shown in the figure.A torque $M$ applied to the outer ring ...
user471651's user avatar
4 votes
3 answers
160 views

Finding downward force of lever bar

I am working on a DIY project, I am trying to replicate a bar compressor which for some reason is only sold in Europe so I thought it would be fun to make my own without having to waste so much ...
Stan-Lee's user avatar
4 votes
1 answer
2k views

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 ...
Graviton's user avatar
  • 1,264
4 votes
1 answer
58 views

How to apply static failure criteria for bending stress in an angled cylindrical surface?

Let’s say I have an irregularly shaped bearing with a cross section that looks like the angled surface of a conical frustum, shown below. If a bending moment is applied which causes the inside ...
juggling_pro's user avatar
4 votes
0 answers
158 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. ...
William B.'s user avatar
3 votes
3 answers
1k views

Why does the minimum force have to be parallel to the incline?

If we have an object on a frictionless inclined bench, why does the minimum force applied to keep it steady have to be parallel to the incline (or perpendicular to the reaction force)? In other words,...
Elruz Rahimli's user avatar
3 votes
2 answers
583 views

Why do we always need to calculate the 'Moment of Inertia' about neutral axis for bending?

I was having a look at the bending stress derivation in few of the books. The derivation indicates how each of the element in the bending stress equation is derived into that equation. However, for ...
Rameez Ul Haq's user avatar
3 votes
3 answers
17k views

What are the units used in beam bending equations? Do they matter?

I was just wondering whether or not the standard beam bending equations worked for all units. E.g. imperial and metric etc. From what I'm guessing it shouldn't really, since once we plug everything in ...
TwoWaySpeedOfLight's user avatar
3 votes
3 answers
9k 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 ...
Rohit Joshi's user avatar
3 votes
2 answers
2k 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 ...
Skipher's user avatar
  • 179
3 votes
2 answers
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 ...
user3233's user avatar
3 votes
2 answers
290 views

How exactly do forces transfer in different directions?

If we imagine the load being placed at the top of the below triangle, I realise that the downwards force is transferred into one which goes in a 'south east' and 'south west' direction down to the end ...
Nick Cory's user avatar
3 votes
6 answers
6k views

Do flexible water hose cause pressure drop with constant flow?

My dad has a tub by a lake. He has a water pump in the lake to pump up water into a tub. He claims that if he use a flexible hose, the pressure in the hose at the top will be lower than if he use a ...
Enselic's user avatar
  • 153
3 votes
2 answers
2k views

How does the number of braces in a balsa wood tower affect the load capacity?

I am deciding between two design ideas for a project in which I have to build a balsa wood tower that can maximize load weight and minimize structural weight (maximize efficiency). I've included a ...
Saahil Chadha's user avatar
3 votes
1 answer
885 views

Car which can climb the ramp of higher inclination

Two automobiles both of which have the mass center located midway between the front and rear axles,are identical except that one is front-wheel-drive and the other is rear-wheel-drive.The cars are ...
user471651's user avatar

1
2 3 4 5
7