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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2answers
486 views

Rigid body equilibrium word problem

In my 100-level university physics course, we are just starting to touch on rigid bodies and tension. While I am fairly certain that I approached this the right way, I would appreciate if someone ...
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2answers
267 views

Forces on a ladder leaning against a box

My question is based on the following problem: A ladder of length $l=3\mathrm{m}$ is leaning against a box with height $h=2\mathrm{m}$ so that the angle between the ladder and the ground is 60 ...
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1answer
625 views

Problem regarding Buoyancy forces and Archimedes principle

A thin-walled container of mass $m$ floats vertically at the separation surface of the two liquids of density $ρ_1$ and $ρ_2$ . The whole mass of the container is concentrated in the part of height $...
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3answers
830 views

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 ...
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6answers
4k views

What is the role of pillars in bridges?

As I can see in the picture, there are so many pillars which are holding the bridge. This picture gave a question to me that what are these pillars doing below the bridge?? An appripriate answer ...
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3answers
95 views

How $4$ forces achieve equilibrium? [closed]

Two identical uniform rods, each of weight $W$, are hinged together to form a structure which is resting on a rough floor as shown. If the reaction forces acting on the structure by the floor are $...
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1answer
65 views

When will the block lift up the front wheel? [closed]

Here is my problem: the luggage is being pulled with force $T$ at an angle $\theta$. I'd like to know when the front wheel will lift up. How do I even start? Before lifting it up, all I know is that ...
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1answer
100 views

Calculating forces in stucture [closed]

I know how to find the reaction at a A and E and they worked just fine with me as external forces. But I am not understanding how to find the forces at joints B and D, what is the approach ?
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0answers
25 views

Find agle for equilibrium [closed]

If someone could help I'd be greatful. The data of the problem are: Mass of the 2 blocks : 2Kg each Mass of the ring: 4*Pi Kg Find the angle theta. I have found that the normal at the floor is : 4g(...
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1answer
650 views

Moments of a barbell

For a barbell with 1. heavier weights near the centre heavier weights near the end (invert the order of the weights in the picture below) Will the barbell with heavier weights near the end be ...
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1answer
218 views

Reaction forces in pyramid stacking of steel coils

I was tasked with solving this problem at work as we are out of coil holders and we bought 140 coils and need to stack them asap. Companies that make the storage holders are on back order for several ...
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1answer
760 views

Leaning ladder reaction force

Shouldn't the reaction force by the ground act along the direction of the ladder? under what conditions will it be along the ladder. What causes the direction of reaction force to not act along ...
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1answer
189 views

Moment of a force convention?

Two forces P and Q pass through a point A which is 4 m to the right of and 3 m above a moment center O. Force P is 890 N directed up to the right at 30° with the horizontal and force Q is 445 N ...
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2answers
763 views

Solving a problem using Newtonian mechanics and D'Alembert principle

yI have to solve that problem with two methods (applying Newtonian mechanics and the D'Alembert principle. The problem consists in two balls inside a spherical cylinder, it consists in determine the ...
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1answer
99 views

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?
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2answers
245 views

Equilibrium of a tower of 2-d blocks

In the image below, All the blocks are frictionless & identical with side of unit length, height $h$, weight $w$ & center of gravity at their geometric centers. The 2 lowest blocks are on ...
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2answers
2k views

Vehicle weight distribution [closed]

I've been creating a 2D (above view) vehicle simulation as a hobby project, and (as is often the case) a problem which I assumed would be simple has turned into the sticking point of the project. ...
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2answers
548 views

Influence of couple-moment's position on bending moment diagram

The moment of two equally opposing force would create a couple-moment. Since the couple-moment value is invariant to the point considered to calculate the couple-moment, I can replace the two equally ...
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2answers
561 views

D'Alembert's principle : static equilibrium of two inclined rods in frictionless rectangular well [closed]

Two rods of length $2a$, masses $M$ and $m$, are in static equilibrium inside a rectangular well of dimensions $a \times 2a$. What are the equations that fix $\phi$ and $\psi$? (One has a "mechanical" ...
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1answer
1k views

Find the potential between two non-conducting parallel planes [closed]

How would I solve the following? Two uniformly charged, infinite, nonconducting planes are parallel to a yz plane and positioned at x 50 cm and x 50 cm. The charge densities on the planes ...
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2answers
412 views

Static Equilibrium with 3 tensions [closed]

Hey guys, for the question that asks you to determine the tension in all 3 cables I am kinda confused. My teacher said the 2nd tension opposes gravity, so it is equal to gravity. then you can equate ...
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1answer
2k views

Estimate the reaction force on each leg of a 4-legged table

Assume you have a table with four legs with a weight placed somewhere inside the boundary created by the legs. The task is to determine the reaction force at each leg. Here are the problem ...
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1answer
1k views

How much would this shelf support? [closed]

Consider the following scenario: I am would like to mount a shelf to my wall. To support the shelf, I am using two drywall anchors, which each are rated at 50 lbs. If each anchor is placed on one end ...
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1answer
54 views

Does it make sense to compute moment of force about any axis?

This Wikipedia article gives that If the unit vector along the axis is $e$, the moment of force about the axis is defined as $$M=e \cdot M = e \cdot (r \times F)$$ Then gives an example which I ...
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1answer
145 views

Finding normal reaction [closed]

In the given figure, find the normal reaction applied by surface OB and OC on spherical mass m = 10 kg as shown
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1answer
508 views

How to find static friction coefficient and the applied force's angle of inclination with a horizontal plane?

Okay so I have this weird problem in my statics book that wouldn't come to a solution no matter what I tried. It states the following: A body of weight $4$ kg.wt is placed on a horizontal rough ...
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1answer
148 views

Differences between these four branches of physics

I am wondering what are the main differences between these four branches of physics: Statics, Kinematics, Dynamics, and Kinetics? And whether the following relationships are correct or not? Statics: ...
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1answer
497 views

Sum of all Moments around an axis as a nonzero number in Statics [closed]

Good time of day, everyone! Here's one thing I can't quite grasp on. So given a Statics problem, I have: $ΣM_x = 159 \;\mathrm{N\cdot m} ≠ 0$; (Sum of all moments around x-axis equals 150 N•m) Now, ...
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1answer
332 views

Equilibrium of rigid body [closed]

A uniform beam $AB$ of length $2l$ rests with end $A$ in contact with rough horizontal ground. A point $C$ on the beam rests against a smooth support. $AC$ is of length $\frac{3l}{2}$ with $C$ higher ...
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2answers
2k views

Minimum force needed to keep the book from slipping?

I would just like to know if my answer to part C is correct because I am confident in parts a and b, Also note that 51.5N is the wrong value for P. P=515N. Ok so since P= normal force, this means ...
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2answers
119 views

Balancing Orthogonal Forces on 2D plane with arbitrary placement [closed]

I have a rectangular block in the xy plane with the center of mass that acts in the z direction at an arbitrary place in the plane. I also have 4 legs that support this weight underneath the block. ...
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1answer
103 views

Why is shear force indeterminate at a section where point load acts

Why is shear force indeterminate at a section where a point load acts, i understand it from the mathematical point of view, since the left and right hand limits would not agree and would lead to ...
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1answer
228 views

Stuck on certain types of static equilibrium problems [closed]

I'm not looking for a direct answer, more like something that can get me started. A lot of the other problems like this were easier, but I'm just lost. This concept seems really difficult to me in ...
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2answers
581 views

Why moment equilibrium must be calculated around the center in this problem?

Consider this problem, which ask for the value of the two normal forces (friction is negligible). Easy, right? You calculate the moments around G, the center of mass, and equate them to 0 (the object ...
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1answer
109 views

Rope tension definition

What is the exact definition of the tension of a rope? Here http://web.mit.edu/8.01t/www/materials/modules/chapter08.pdf the following definition is given The tension $T(x)$ in a rope at a ...
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1answer
655 views

I need help with determining angles after shifting of axis in Free Body Diagrams

I can't figure out by which property of the triangle the angles in shifted axis are also 30 degrees. Vertical angle theorom doesn't work. I drew it again and again. If someone could draw me a diagram, ...
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1answer
457 views

Stuck on a static equilibrium problem [closed]

This is the problem: "The figure below shows a 25-foot sailboat. The mast is a uniform 119-kg pole that is supported on the deck and held fore and aft by wires as shown. The tension in the forestay (...
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1answer
47 views

How would you get the velocity in this problem? (and what did I do wrong) [closed]

This problem is supposed to be solved by using the conservation of energy but I do not really know how to solve it that way.
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1answer
58 views

What component of the payload appears on the cross member? [closed]

I have a set of DIY steps; I've modelled it as the steps themselves "s", a short vertical support "a", a long vertical support "b" and a cross-member "c". Here's a picture: Just to be sure I modelled ...
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4answers
665 views

Draw the Free Body Diagram

Question: Draw the Reaction Force at point P. My Attempt and Reasoning: Since the Reaction or the Normal Force is normal to the surface the solution according to me should be- However, the correct ...
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1answer
176 views

Basic tension and equilibrium confusion

The following is what I did: $$Fsin\theta = 60 => F = 93 N$$ $$Fcos\theta = 40 => F = 52 N$$ Why do I get different results? Does this mean the object isn't in equilibrium? How can I proceed ...
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0answers
256 views

Axial loaded bars problem

I completely disagree with the following calculations: Based on my understanding, there is no force either internal or external applied to the Green bar, so it should be 0N. The reaction (internal) ...
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1answer
150 views

Why curvatures relieve stress?

Per example, we can stop a crack in a steel plate by drilling a hole at the end of it. Or we all know the famous example of popular science that airplane windows are round for the same reasons. Why ...
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2answers
1k views

Mass required to prevent sign falling over with a set wind load - activity stations for disabled children

I'm currently working on my thesis and I'm stuck on a question. I'm designing activity stations for disabled children to be used for equine therapy. The stand is 9ft tall and I've calculated the the ...
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1answer
2k views

The Physics Behind the American Death Triangle [closed]

I've heard a lot about the American Death Triangle and how it is awful for belaying. The Death Triangle is set up as such: you have two anchor points with a single rope or line running through both ...
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1answer
1k views

Calculating force with two fulcrums and many forces [closed]

I may not be wording the question the right way. I have a lever. About 2/3 the way back there is a pivot point. We'll call this B On the very front (end of the lever) there is a block that the lever ...
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3answers
1k views

Do supports exert torque?

I think I'm missing something about torques. Do supports exert torques? Consider these two situations I'm confused about. A rod is attached in to a wall so that it cannot rotate. Since weight exerts ...
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1answer
402 views

What are the clicking sounds when static electricity occurs?

Sometimes, when there's static electricity, soft clicking sounds can be heard. This may happen when two fabrics are rubbed or when you get a static shock. What exactly causes this sounds?
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0answers
87 views

What way did this person solve the problem? [closed]

Im curious, I have no idea how they solved the problem to get from the unitary vector to the Moment/Tension. How did they managed to get it so reduced? What steps did they perform in the blue part?
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1answer
531 views

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 ...