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Questions tagged [statics]

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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Moments and Equilibrum [on hold]

Q: A uniform cylinder has height 10.0cm and diameter 3.0 cm. The cylinder is placed with its circular base resting on a horizontal table. Calculate the maximum angle through which it can tip before it ...
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1answer
42 views

Formula for would something fall over or not?

Let's say I have a 10cm x 10cm x 50 cm wooden stick that weights 5kg total. The 10cm x 10cm base is touching the floor and it protrudes from the floor 50cm which is the height of the stick. Based on ...
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0answers
31 views

How do I solve for Tension 1 and Tension 2 in this problem given the weight is 100N? [on hold]

How do I solve for Tension 1 and Tension 2 in the problem? The weight is 100N. Book is BREAKING THROUGH SCIENCE 10; Page 88, Number 4 Problem Three
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30 views

help this tension problem Weight is 100N [on hold]

help i dont know tension please help send help please physics gods help help help please. Thank you
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1answer
33 views

Three cylinders stacked [on hold]

Im stuck in a mechanics problem. Three cylinders with the same mass, radius and large are arranged as follows. The coefitient of friction is $\mu$. Calculate the critic $\mu$ for the system to be ...
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0answers
11 views

Repositioning Moment Center [closed]

I was given the following problem: The 520-kg uniform beam is subjected to the three external loads shown. Compute the reactions at the support point O. The $x$-$y$ plane is vertical. Positive values ...
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0answers
19 views

Applying torque on static structure [closed]

Hi all, Please consider the attached picture, which shows a mass-less rigid body. This body is pinned/screwed on points A and B, and a torque with intensity "M" is applied with an axis on point C. ...
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1answer
80 views

Three Dimensional Torque on a Sphere

Assume that we have a sphere in 3D space. Let point $A$ rest on the surface of the sphere. I can apply a force $F$ of any magnitude and any direction, so long as it points tangential to the surface ...
1
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1answer
31 views

Magnitude of F about line CD (Mechanics, 3D vector system)

I am having trouble with this question: I will write out the question below to make it easier for other people googling the question to find it: 2/139 If the magnitude of the moment of F about line ...
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0answers
24 views

Good book on Statics and Dynamics [duplicate]

Could you please suggest a good book on statics and dynamics. The portions I have to cover include Statics : Equilibrium in 2&3 dimensions, Virtual work,Common catenary etc Dynamics : ...
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1answer
47 views

How can I measure some forces in this experiment…? (statics)

Math and statics weakling here trying to do some... math and statics. I have an experiment where I'm trying to measure forces along 2 axes. I currently have a setup that I think might give me the data ...
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0answers
29 views

Derivation of friction in interleaved phonebooks

Trying to understand the simple model in https://arxiv.org/abs/1508.03290, describing the friction between the pages of two interleaved phonebooks. Specifically I don't see how to get Eq. 1. Here's ...
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2answers
89 views

Magnetic levitation against Earnshaw's Theorem?

Given six strong magnets, what if we fix three of them to a table in a simple, horizontal, equilateral triangle-like formation (with their north poles sticking up), and the other tree to the points of ...
2
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2answers
41 views

Why are ropeway pillars tilted?

While skiing I have noticed that ropeways pillars are usually tilted to be perpendicular to the slope (fig.1). If the gravity is pulling straight down, why aren't they vertical as they are supposed to ...
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0answers
40 views

Rotor finds equilibrium in TWO positions, why and how?

I have a Mendocino motor, a toy with magnets, solar panels, and coils. Such a thing requires careful balancing (eg. with tiny bits of tape) to achieve sufficient balance that it will start rotating ...
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3answers
47 views

How does beam pinned at one end resist moment?

This beam is constrained by a pin at one end, so it is free to rotate around that point. If a moment M is applied, the beam cannot move since any rotation would involve motion of the COM, which is not ...
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1answer
22 views

Stability of a falling object

Suppose there is a falling object that has flaps around it providing resistance to the non-contact force of gravity. How would the vehicle theoretically not flip over? From my understanding, the ...
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1answer
50 views

Balanced Torques and centre of mass

Say we have a plank of wood that is placed on the edge of a cliff so that one end projects horizontally out over the edge. How would you go about finding the minimum mass that you could place on top ...
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0answers
23 views

What analysis should I make when there is toppling question without specified axis? [closed]

For example - What maximum weight can be put on a table of 20 kg and radius 1 m with massless leg which are symmetrically placed on circumference so, it doesn't topple? Here, I don't know how to ...
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2answers
43 views

Does mass affect how likely an object is to topple over?

I was at work recently pulling around some pallets when I had a thought. I wanted to know if the mass of the pallet had any influence on how likely it is for the pallet to topple over when going ...
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1answer
111 views

How to calculate the max load a metal bar can hold?

How would one calculate the amount of weight a steel bar could hold before breaking? Apologies for the terrible diagram. So if I had a steel bar of the length 18in, and the cross-section with a ...
1
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1answer
70 views

Rod that is toppling over

A rod is about to fall over. If $N=mg$, then there is no resultant vertical force acting on the object. So how is the object able to fall over? Intuitively I understand why it would fall over but ...
0
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1answer
63 views

How do I calculate the maximum force needed to apply on the structure for it to topple over? [closed]

The structure consists of 6 parts as shown and the purpose of this structure is to be placed in construction sites to monitor the progress of works. As such, the structure will be subjected to ...
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3answers
95 views

Torque on a shelf

Say I have a shelf anchored to the wall (how it's anchored doesn't matter here I think), with a mass (m) taking up most of the space on the shelf: Say the shelf is x meters long, and the mass is y ...
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1answer
95 views

Proof of the Law of the Lever

Is there an accepted proof of the Law of the Lever? I know of several attempted proofs, such as Archimedes's, but these either are incomplete or do not transfer to the setting of Newton's Laws. (It ...
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2answers
44 views

Is the method of joints only applicable to trusses?

I am confused as to whether the method of joints is only restrained to pin-jointed trusses or it can be applied to other statics problem, for example the one shown in the picture, and why?.
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2answers
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Tangential Contact forces between objects

My book says that there are two forces two objects experience when they're in contact with eachother. (it uses an example of a cylinder and a parallelepiped that are in contact with eachother) The ...
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2answers
119 views

How would I draw the forces on two identical ladders propped up against each other, connected by a rope?

Two ladders of uniform density and equal mass m are propped up against each other at angles $\theta$ from the frictionless ground. A rope of tension $T$ connects the two horizontally a distance $\...
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1answer
164 views

Statics problem: Finding resultant force angle measured from positive x-axis

I have this diagram: And I have done these calculations: $$R_x=-20sin(30)+30cos(35)+80cos(45)=71.14 \; lb$$ $$R_y=20cos(30)+30sin(35)-80sin(45)=-22.04 \; lb$$ The magnitude of this resultant force is ...
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2answers
42 views

From Where Did The Table Get Energy? [duplicate]

When a block in resting on a table (the table is on Earth) the table stops the block from going more down, from where does it get the energy to apply a force opposite to gravity?
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2answers
330 views

Beam attached to a wall

Suppose I have a rigid beam attached to a wall, how can the reaction force on the point the beam is attached to generate a static equilibrium on the beam? ...
1
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1answer
58 views

Virtual work - Tension in a string

I am confused about the way Tension or Thrust is used in equation of virtual work. I mean whether to use $ T\cdot dr$ or $-T\cdot dr$ (work done by tension). For instance in the below case : A ...
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votes
1answer
224 views

Ladder and friction (wall and floor) [closed]

Here there is a problem and the proposed solution: UPDATE: I can't understand why getting the maximum friction to solve this kind of problem when it is known that static friction, depending on other ...
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2answers
127 views

What is the maximum force you can exert on the ground with one leg? [duplicate]

You are standing on hard floor. Clothes weigh negligibly. You move only your leg. Everything else remains stationary. Assume you are made of the same material as the average human. Can the force ...
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0answers
43 views

Base length and Mass required to stabilize a large heavy sign [closed]

I have an 8ft x 7.5ft sign that is about 4inches thick and weighs about 150lbs. We can assume the whole thing is made of the same density I am building the stand for this and I cannot anchor it to ...
2
votes
1answer
49 views

Is there a name for this phenomenon?

Imagine I have a cylindrical pipe closed on both ends with lids. I fill it with sand and compress the sand tightly. Now I hold the cylinder vertically and remove the bottom lid. The sand will counter ...
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1answer
180 views

Tipping angle of a box [duplicate]

how do you calculate the tipping angle of a box? That is the maximum angle a which a box can reach before tipping over. help, please!
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4answers
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Why is the shape of a hanging chain not a “V”?

From Wikipedia: To answer this question: "What is the shape of a chain suspended at both ends?" we can use the variational principle that the shape must minimize the gravitational potential energy. ...
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1answer
2k views

3 people carry a log of wood, which one is carrying the most weight [closed]

I saw this on a youtube video. The answer is that the one in the middle is carrying 25 % more than the other two. Can someone explain this?
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2answers
495 views

Varignon's theorem (Principle of moments) failure?

Varignon's theorem states that "If many coplanar forces are acting on a body, then the algebraic sum of torques of all the forces about a point in the plane of the forces is equal to the torque of ...
1
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1answer
60 views

A question about temperature in the concept of a macroscopic statistical-mechanical system

I recently have come across a question while working on Statistical Mechanics. The question itself was quite straight forward (no this is not a "do my homework" question in case you were wondering) ...
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2answers
60 views

Power in 1st Gear

The max power an engine puts out is what determines the max speed a car travel at right, obviously it's more nuanced than that because there are losses in the drive train, and the shape of the car ...
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2answers
124 views

Finding the equation of a chain hanging between two points

Say I have a connected at either end to two points, $A(x_A, y_A)$ and $B(x_B, y_B)$ of length $l$, where $l \leq \sqrt{(x_B - x_A)^2 + (y_B - y_A)^2}$, how would I go about finding an equation of its ...
1
vote
1answer
168 views

Conditions for Static Equilibrium of Rigid Body [duplicate]

When there are forces acting on a rigid body, the two conditions that has to be satisfied for the body to be in static equilibrium are: 1. The sum of all forces must be zero (translational equilibirum)...
1
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1answer
259 views

Work done in lifting a object from underwater if it displaces $W'$ of water? [closed]

A spherical shot of W gm weight and radius r cm, lies at the bottom of cylindrical bucket of radius R cm. The bucket is filled with water up to a depth of $h\,\mathrm{cm}$ $\left(h > 2r\right).$ ...
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votes
1answer
98 views

Why can't a pyramid stay balanced on a vertex? [duplicate]

A pyramid, such as a tetrahedron/3-simplex, or any other isohedron, falls from some height and lands on a vertex. It will eventually end up with a face to the ground. Why can't it stay balanced on a ...
2
votes
2answers
78 views

balancing a weight on a table without tipping over

I have a statics problem. Here is a model for a table: a circle of radius 1.5 ft a pole in the center a base in the shape of an X. I place a weight on the table on the edge. How much weight can ...
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1answer
38 views

Equation to model change in leverage point

Is there a mathematical model for the situation below? First, I want to know how much force I would need to lift this block some distance using this wooden board. The block is situated against a wall ...
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0answers
57 views

How do bicycle pedal forces resolve?

If you're standing on a stationary bicycle, with pedals at 3 and 9 o'clock, how do the forces resolve if you shift your weight over the rear pedal? Most weight is on your back foot. Since your front ...
0
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1answer
356 views

Static equilibrium- when do you use forces and when do you use torques?

I'm working on an answered physics question in the book but I'm having trouble understanding why the problem could be solved by setting net torque equal to 0 and not net force. You are asked to find ...