The statics tag has no wiki summary.
3
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2answers
49 views
Why are some jenga pieces easier to remove than others?
Jenga is a game place with wooden blocks stacked on top of one another in an alternating pattern. Players take turns removing blocks from any layer and placing them on top.
As the game progresses ...
0
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0answers
21 views
The stress in copper and steel parallel compound members [closed]
Came across this question and just needed abit of help undertanding how i should go about this question
I have also attempted to solve it to the best of my ability but im stuck.
A concrete column of ...
2
votes
1answer
57 views
Tension in a closed loop around an object, carrying stuff
Sorry when this sounds like a first year physics homework question, but it's actually not. It arose during a discussion regarding safe practices for rock climbing anchors...
So here we go: Imagine ...
12
votes
5answers
1k views
Why Won't a Tight Cable Ever Be Fully Straight?
I posted this picture of someone on a zipline on Facebook.
One of my friends saw it and asked this question, so he could try to calculate the speed at which someone on the zipline would be going ...
1
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4answers
2k views
Upward force on a object at rest
Is there an upward force on a object at rest? If yes, where does it come from?
1
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1answer
75 views
Force analysis on truss
I am reading a book on fundamental physics for mechanics. There is a truss shown in the figure. A train of mass $M=56$ ton is resting at the middle point of AC, ignore all the mass of truss and rails. ...
0
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1answer
55 views
Statics Moment Diagram
I am having troubles converting my shear diagram into a moment diagram. Either I am doing something wrong or MasteringEngineering is incorrectly marking it wrong. Anyway here is the problem/correct ...
1
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1answer
437 views
Solving a Statically Indeterminate Truss with Energy Equations (Tricky)
Okay, first off, I know that there is a very similar problem about statically indeterminate trusses here, but my problem was a bit different and I didn't know how to adapt the answer for that problem ...
0
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1answer
444 views
Solving an indeterminate triangle truss structure (statics)
From the setup of two trusses as shown in this illustration, how can I solve for the axial reaction forces in the trusses, and in the points A and B (Ax, Ay, Bx, By)? It is assumed that the joints ...
2
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1answer
83 views
Statics of Rigid Bodies — Can there be two possible solutions?
I've been working on a question and there seem to be two possible solutions. My own solution does not match the one given in the book. However, after resolving forces and taking moments with both ...
3
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3answers
88 views
Does a cross really have a smaller area moment of inertia than a square of the same area?
I need to calculate the area moment of inertia of a cross for a homework assignment. The cross is a symmetric plus sign:
_
| |
|== ==|
| |
-
...
0
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1answer
89 views
Problem solving moments in equilibrium
Two straight ladders, AC and BC, have equal weights $W$. They stand in equilibrium with their feet, A and B, on rough horizontal ground and their tops freely hinged at C. Angle CAB = 60$ ^o$, angle ...
4
votes
1answer
85 views
Application of Archimedes Principle
A candle is floating in a liquid placed in a container. The container is a cylinder of diameter $D$, and the candle is of width $d$. ($D>d$) The height of the liquid from the bottom of the ...
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1answer
32 views
Find the bending moment of a pole attached to a moving block
I'm having trouble with the following problem.
What I've done so far:
x-y is the usual coordinate system.
$a=\frac{F}{m}=\frac{800}{60}$ and the y component of this is $a_y=a\sin{60^\circ}$.
To ...
0
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0answers
72 views
Tension $T$ in cable [closed]
Calculate the tension $T$ in each cable, as well as the magnitude and direction of the force exerted on the strut by the pivot in each case mostrados.En systems, w is the weight of the suspended box, ...
1
vote
1answer
137 views
Cylinder rolling down an inclined plane held by a string
A cylinder of mass M and radius R is in static equilibrium as shown in the diagram. The cylinder
rests on an inclined plane making an angle with the horizontal and is held by a horizontal string
...
4
votes
1answer
513 views
Hooke's Law question
I have the following question to answer:
a force of160 N stretches a spring 0.050m from its equilibrium position.
A. what is the spring constant of the spring?
The equation for Hooke's Law in my ...
5
votes
3answers
224 views
Force between two charged rods?
Suppose that we have two rods of length $l_1, l_2$ connected at one end but free to rotate. These rods have charge density $\lambda$ uniformly distributed, so the total charge of rod $i$ is $\lambda ...
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0answers
27 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. ...
-1
votes
1answer
261 views
Internal forces in a truss and its geometry
I'm to work out the internal forces in a truss, but I can't get my head around the geometry of the truss itself. I'm starting to think there may have been information on the diagram which I missed. ...
3
votes
2answers
865 views
Calculating torque adjustment for offset of pivot point
I'm trying to figure out how much to adjust torque, on a torque wrench when using an extension that offsets the pivot point. See this calculator for a diagram of what I'm talking about:
The trouble ...
1
vote
2answers
100 views
Additional mass of block on inclined plane
I would like some help in solving this problem.
Height is 15 cm , base is 88 cm
My attempt:
$$(119.3 + m)(\sin(\theta)) = (88*9.8)$$
$$ 15^2 + 88^2 = 89.269^2 $$
$$ \sin^{-1} = 15/89.269 $$
$$ ...
0
votes
1answer
430 views
Calculation of a bending moment
I'd like to calculate the bending moment of a cantilever, fixed at its base, and submitted to a certain stress on a specific spot, but I can't find the proper definition of this bending moment (first ...
6
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2answers
601 views
Hydrostatic friction: why do water droplets stay at rest on an inclined glass surface?
Tjis is a non-expert question on a (seemingly simple) text-book topic.
The question is about "hydrostatic friction", defined as follows.
Consider a drop of water resting on a flat surface. If the ...
0
votes
1answer
140 views
Relationship between torques and centre of mass or centre of gravity [closed]
1) A wardrobe is $2$m high and $1.6$m wide. When empty, it has a mass of $110$kg and its centre of gravity is $0.8$m above the centre of its base. What is the minimum angle through which it must be ...
0
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0answers
151 views
How to solve fixed-fixed beam with finite difference method?
What equations to use on this system to form a matrix $A$ with dimensions $[n,n]$ and load vector $q$ with dimension $[n]$ ? I am trying to get vertical displacement $w$.
$$w = A^{-1}\times q$$
...
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0answers
55 views
How can I calculate all of the tensions in the cords? [closed]
I have been stuck on this problem for the last half, and to be honest I don't even no where to begin. I'm being asked to calculate all of tensions for the cords. I know I'm supposed to use $\cos$ to ...
4
votes
3answers
602 views
Hanging chain in a planet's gravitational field
The curve for a chain hanging between two poles in a uniform gravitational field is known as the catenary.
Is there known an expression for the curve of a hanging chain on a planet of mass $M$ which ...
3
votes
0answers
172 views
Shape of a string/chain/cable/rope?
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 ...
0
votes
3answers
134 views
Doubts with levers
I'm studying for a test of static rigid body and I'm having doubts on how to solve problems involving levers with weight.
If I have, for example, a lever 10 kilograms and 3 meters long and one support ...
2
votes
3answers
508 views
Statics software for structural engineering
I'm attempting to expand my knowledge of engineering software. I've found comsol and ansys for acoustics and thermodynamics/fluid dynamics (not necessarily in that order), now I'd like to see if I can ...
3
votes
2answers
207 views
Bowling ball on a rubber sheet
After reading a layman's guide to general relativity, I began to wonder what shape a bowling ball on a large rubber sheet would produce. For simplicity, I would like to assume that Hooke's law applies ...
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1answer
633 views
How to calculate the supporting force for a cantilever beam? [closed]
How do I find the supporting force $R_A$ and the moment $M_A$?
Should I use the sum of moments or?
0
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1answer
186 views
Trying to understand the tension in a spring with two weights attached [duplicate]
Possible Duplicate:
Why I think tension should be twice the force in a tug of war
For (A) in this image, I would think the tension should be should be 2mg.
However, my book says the ...
0
votes
1answer
212 views
Can I use Newton's second law to solve what seems to be a torque problem?
The Problem:
An 8-m-long beam, weighing 14,700 N, is hinged to a wall and supported by a
light rope that is attached 2.0 m from the free end of the beam. If the beam is
supported at an angle ...
2
votes
1answer
94 views
Can structural trusses in centrifuges be helpful at all?
Imagine a rotating space station for the purpose of creating artificial gravity. Generally, such a space station is portrayed as a ring or a cylinder. Images of these space stations often have lines ...
4
votes
1answer
741 views
Solving a statically indeterminate truss
I'm trying to solve the statically indeterminate truss shown below and I'm having a little trouble.
$H$, $P$ and $\beta$ are given. The material is aluminum (density is 2700 ${kg/m^3}$) and has a ...
1
vote
1answer
60 views
Force in tetrahedron edges
I am looking for a formula that enables me to calculate the force in a tetrahedron edge such that it relates $F_b$ with $F_z$ through the beam thickness and length. I have the following assumptions:
...
3
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0answers
90 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 ...
3
votes
1answer
567 views
If 1 screw can support 120 lbs, how much weight can 25 screws support?
While this is mainly about my personal home improvement project, I figure this would be a good opportunity for some of you to apply your physics skills to a real-world situation.
My situation is ...
0
votes
1answer
276 views
Torque and equilibrium
I am a little stuck on the concept involved in part b) of the following problem:
A $5 m$ long road gate has a mass of $m = 15 kg$. The mass is evenly distributed in the gate. The gate is supported at ...
3
votes
1answer
355 views
Understanding moments as forces?
I was watching this lecture on analysis of stress for mechanics of materials. At time 7:20, the lecturer says that in equilibrium, the sum of forces and "moments" in each direction (x,y,z) must be ...
0
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1answer
327 views
Calculating torque in a structure
I posted this on math stack exchange but realize it is more a physics question.
I have a structure which is set up as shown in the image. A weight hangs from point A with mass $m$. Joint B is free ...
2
votes
1answer
527 views
Relationship between balloon size and pressure
I see numerous websites talking about how a small balloon is at higher pressure than a big balloon. This is a fun counter-intuitive factoid... unless it isn't a fact at all.
Young-Laplace gives
$$T ...
1
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2answers
559 views
Calculate the weight a simple plank can support
I'd like to build a simple desk; just a single plank of wood (or a few side-by-side) with solid supports on each end of the desk. What I'm trying to figure out is how thick a plank I want to use for ...
0
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2answers
736 views
Calculation of the maximum load to the bar
Looking for a way of calculating the maximum weight (W) to the rod with the given length (L) where the rod did not break and that only bend for (b) mm.
Need only approximative solution (read: ...
2
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2answers
866 views
Angles on swing sets
I'm building a swing set for my children. All of the designs I've seen involve building two A-frames and connecting them at the top with a crossbar/beam from which hang the swings. The A-frames are ...
2
votes
1answer
277 views
Why does the beam in a weighing balance get tilted proportional to the weights added to each pan?
I'm talking about a beam balance(a simple weighing balance with a beam and two pans hung on either side)
As answered in a previous question, the beam comes back to the original position when one ...
0
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2answers
178 views
Hanging a Hammock
I have a hammock that I want to hang using a tree on one end and a wooden post set in a bucket of cement on the other end.
How would I determine how heavy the cement needs to be so that it would ...
3
votes
3answers
190 views
What is a “Center Of Mass” issue of a Gorillapod?
I read somewhere that a Gorillapod may have "Center Of Mass" issues when used with the long lenses.
So, I wish to understand what is a "Center Of Mass" issue?
I have to clarify that I am NOT a ...
