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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2
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0answers
23 views

Distribution forces

I've got two trees and between them is a rope. When someone about 100kg sits at the center of the rope, what are the forces on both parts of rope (to the left-hand side from the person and right-hand ...
1
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1answer
950 views

Calculating torque in 3D?

Say you have a sphere, and you have several torque vectors acting on it, all at different points. Say you have the vector (6i + 3j + 5k) originating from point A, and the vector (3i + 1j + 9k) ...
2
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1answer
789 views

How to calculate the supporting force exerted by a stationary object (cupboard) and support (brackets) for it?

I have a wall mounted Stuva Ikea cupboard, which measures 60x64x30cm. The base is 64x30cm. It is already supported by 2 holes at the back base, (64x60cm). But I need to add in L shape brackets ...
1
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1answer
44 views

How to calculate the normal force exerted by a fulcrum off-center?

So I know that $F_N$ exerted by a fulcrum right under the centre of mass for, say, a long horizontal rod, is equal to $mg$. But what if the fulcrum is off the centre of mass either to the right or the ...
1
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0answers
32 views

How does force transmit through a solid block?

If you take a solid block, say, a cube of side length $l$ with density $\rho$, you place it upon a solid floor, and you apply an external pressure of $p(x,y)$ on the upper face ($x$ and $y$ define a ...
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0answers
22 views

Statics: Cable with distributed loads. What am I doing wrong?

This is the problem: It says: If the maximum value for the ABCD cable's tension is 15 kN, determine: a) $h_b$ b) $h_c$ My development was: 1) Whole body (ABCD). Sum of momentums in D equals ...
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3answers
134 views

Are circles stronger than triangles?

I've often herd in engineering that "there is no shape stronger than a triangle". I also recall that arches are very strong shapes as well, which can be crudely described as a ...
0
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1answer
51 views

How many bricks can be put without disordering the equilibrium? [closed]

A homogenous brick with length L, is on a horizontal surface. On this brick are put one after another other bricks, which are the same with the first. Every brick is moved along L/5 units horizontally ...
1
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1answer
108 views

Exam review problem. Weird answer [closed]

The question asks us to calculate the holding force of the triangular mounting if the rock weighs exactly $2kg$ and the mounting supports the rod at exactly $\frac{1}{4}$ of its length. ($g=9.81 ...
-1
votes
1answer
38 views

What does $\bar{x}_{\textrm{el}}$ represent?

In the context of centroids and moments, what do $\bar{x}_{\textrm{el}}$ and $\bar{y}_{\textrm{el}}$ represent? For example: $$\bar{x}L = \int \bar{x}_{\textrm{el}}dL$$ Some references that use ...
1
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2answers
367 views

Determining the neutral axis of an I-shaped cross section with dissimilar materials

Determine the neutral axis of the I- shaped cross section with dissimilar materials. The top rectangle of the cross section is made out of aluminum and the second and third part are titanium ( these ...
0
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1answer
68 views

Calculate reaction forces, bending moments and shear forces, udl=0.5kN/m

i have reaction forces of Ra $= 7.890625N$ & Rb $=1 03.359375N$ my shear force calculation equates to 0N at 5.5m which i believe is correct however i am having trouble getting the bending ...
-1
votes
1answer
466 views

Internal forces in a truss and its geometry [closed]

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. ...
0
votes
2answers
56 views

What is happening when a jenga block tower wobbles?

Imagine I am 3/4's of the way through a Jenga wooden block game. I have a tower and it is starting to wobble. To me it seems there are two possible causes for this: the wood is compressing and ...
0
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3answers
133 views

Tension Problem: Finding an angle when only given the tension in two ropes [closed]

A crate is hanging from a rope which is attached to a metal ring through which a second rope runs, as shown to the right. What is the angle $\theta$ if the tension in rope 1 is $1.19$ times the ...
2
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0answers
279 views

Mechanics of Materials (pressure and temperature)

A solid right cylinder of rock core is surrounded by four rods made of mild steel (all-thread rods). The rods are placed equidistantly around the core in a square formation. The tops and bottoms of ...
1
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2answers
125 views

Is the center of mass of an object just a convention?

I am currently studying moments. The concepts are fairly obvious, but there is one thing I don't understand: the concept of center of mass. Why do we consider that the weight of a uniform object is ...
1
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1answer
2k views

Calculating mass of object by lifting edge

Assuming a solid rectangular plate, hinged along one edge. How does one calculate the mass of the plate if the force necessary to lift the opposite edge is known?
1
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1answer
48 views

Why can contact force be ignored here?

I was discussing the first part of this question with a friend, and he told me that while taking moments about $A$ and $B$, we can ignore the reaction force at C. Indeed this is correct, because ...
1
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2answers
726 views

Statics with ladder and wall [closed]

A uniform ladder of mass m and length L rests against the wall. The coefficients of static friction between the floor and the ladder and between the wall and the ladder are equal to each other (μ). ...
0
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0answers
31 views

When a force applies to a rigid body at point, then does every part of the body experience the same kind of force?

Suppose that a rigid body is static under the action of several forces that are applied at different part of the body. Then is it true that if one divides the body into small pieces, then each piece ...
-1
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1answer
177 views

Tension of string attached to ball on inclined plane [closed]

A sphere of weight 50N and radius 4cm is held by a string of length 8 cm against a smooth wall inclined at an angle of $70^{\circ}$. Find the tension in the string and the force between the ball and ...
0
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0answers
11 views

Plastic loading of a cylinder

I am trying to model a solid cylinder being loaded in the axial direction. At the upper limit of the elastic loading the cylinder has been compressed to a height h and cross-sectional area A. It is ...
0
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3answers
80 views

What force $\vec{F_{1}}$ is needed to balance the beam in the diagram below? [closed]

What force $\vec{F_{1}}$ is needed to balance the beam in the diagram below? I know that $\sum \vec{F}$ must equal zero. I also know that since the unknown force is farther from the pivot, ...
0
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1answer
62 views

How does the net torque have to be 0 at all points for static equilibrium? [duplicate]

I know that for a mass to be in static equilibrium two things have to be satisfied: $\sum F=0$ and $\sum T=0$, where $T$ represents torque. However, I am not sure how the latter can apply in a ...
-2
votes
1answer
87 views

Tension on strings holding a weight [closed]

It's a 100% standard problem in any basic physics course, and I cannot solve it. Here's the scenario: What is the tension in the strings (T1 and T2)? My thoughts were (cos/sin rewritten as ...
-1
votes
1answer
140 views

Find center of mass and moment applied on beam structure [closed]

I have a simple physics problem to solve but it is giving me a slightly difficult time to figure out. The problem: I have a beam structure with same cross section. It consists of three beam. First ...
1
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1answer
222 views

Parallel axis theorem

For this question we are working in 2-D space. Let's say that we have an arbitrary body. I know the inertia with respect to a perpendicular axis (to the body, that is) that passes through a point (A). ...
1
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2answers
200 views

Weighing with One-Foot Scale

I stand with left foot on a scale and the other on a piece of effectively incompressible material at the same initial height at the scale's top surface. The weight shown is WL. I repeat with right ...
0
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1answer
45 views

How does Centre of gravity influence the equilibrium?

Ok! This really makes hard to think, how does a single point determine the object's equilibrium? If an object is displaced from its equilibrium-position & if the equilibrium is stable, the object ...
0
votes
3answers
69 views

Finding minimum force to hold a particle in equilibrium [closed]

A particle of mass $m$ is suspended from a point A on a vertical wall by means of a light inextensible string of length $b$. Find the magnitude and direction of the minumum force $\boldsymbol P$ ...
0
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0answers
201 views

Ladder equilibrium problem - Where do the hinge forces go?

In my physics homework there is a problem about a hinged ladder like this and a man is standing on one of its halves. The two parts of the ladder are hinged together at the top. My question is, ...
0
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2answers
121 views

Prevent a box from tipping over: height of CG?

I'm on a problem that can be simplified in the following way: A box is placed on a horizontal plane, and is pinned to the ground on one side only such that it can tip over that side. Given a ...
2
votes
2answers
51 views

The principles of statics without force

I'm a student of civil engineering and now my course is covering the basics of statics, such as the equations of equilibrium, etc. Trying to get a better basis on the subject, I started to search on ...
1
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1answer
79 views

Floating objects and fluid statics

If an object is floating, I know about how buoyancy force (density of liquid* volume displaced* g) must equal gravitational force (density of object* volume of object* g). Can someone explain if it is ...
1
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2answers
220 views

Forces exerted on legs of a table

This is actually for a computer science homework problem, but I haven't studied any physics in five years so I'm having a bit of trouble. I'm given a table of three legs with their coordinates and I ...
21
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7answers
6k 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 ...
2
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0answers
16 views

Dropping vertices of an overdetermined statics system graph

In statics, the problem of determining the tensions of K cables that connect a structure made of N points and keep all points in static equilibrium implies $ND$ systems of equations, where $D$ is the ...
0
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1answer
4k 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 ...
1
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1answer
280 views

Choosing the right point when calculating moments

A body is composed of two straight pins that are joined at a right angle. They have lengths $a$ and $b$ and the mass per unit length is $\rho$. When the body is balanced on a flat surface, as shown, ...
0
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1answer
44 views

Torque in a 2-segment robot leg

I have a (hypothetical) robot with two legs, each with 2 segments, with a joint at the body of the robot and in the 'knee' of each leg, as in this (poorly-drawn) diagram: (Sorry about the quality and ...
2
votes
2answers
70 views

Does the distance two weights are from you alter the difficulty of lifting them?

If I am weightlifting and I choose to do the deadlift, does it matter how far away from me the weights are on the bar, given that they are equally distance from me on both sides. E.g. I am deadlifting ...
14
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6answers
3k views

Why does the weighing balance restore when tilted and released

I'm talking about a Weighing Balance shown in the figure: Press & Hold on onside of the horizontal beam and then release it. It makes some oscillations and comes back to equilibrium like shown ...
0
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3answers
3k views

How do I find the tension in additional strings in this problem? [closed]

A mass of 5.00 kg hangs attached to three strings as shown in the figure (see image below). Find the tension in each string. Hint: Consider the equilibrium of the point where the strings join. ...
3
votes
1answer
320 views

How is weight distributed when legs are astride?

Is there a simple and quick formula to find the weight (the force acting) on each leg, especially when legs are astride and they are not equally stretched? (or, better) not equally distant from the ...
0
votes
3answers
365 views

What is the equation for the tension on the ends of a cable suspended at different heights?

I'm looking for an equation to find the tension on the ends of a cable suspended between two poles (one higher than the other) with no load but the cable itself. I determined that the tension would ...
-1
votes
1answer
562 views

Finding the mass of bed/Patient [closed]

One of my friends has a problem and we don't know how to get this done, We want to to know the mass of a patient who is laying on a bed. One scales was put under the foot of a bed and weighed 232kg ...
0
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1answer
36 views

Finding directions of the internal forces within a freely jointed rigid object?

Consider the the following problem: Here is a force diagram showing the situation: For part (i) Taking moments about $B$ for $BC$ gives $84.5Lcos\beta=2LT$ So $T=39$N For part (ii) Resolving ...
3
votes
1answer
175 views

Forces acting on two balls in a jar [closed]

Consider the following situation: Two balls are inside a jar with diameter $D$. The balls are uniform in mass and both have the same diameter $d$. Express the forces that acts at the colored dots ...
0
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3answers
259 views

Topple a mass standing still

Consider the following situation: This is taken from an example from my book with a solution. The box weight is $W$ and the coefficient of friction between the floor and the object is $\mu$. What ...