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0answers
9 views

What angle - for a strut - provides the greatest vertical strength/support for cantilever [duplicate]

What angle - for a strut - provides the greatest vertical strength/support, for the free end of a cantilever
2
votes
2answers
39 views

Wheelie physics part 2

Okay, so I got some really great advice from the community here but I am still hung up on some conceptual problems. I posted earlier trying to determine the axis that a bicycle rotates about when ...
3
votes
2answers
82 views

How does a wheelie work?

So I've been trying to create a mathematical model for an electric motorcycle and began to wonder about the maximum possible torque that could be supplied to the rear driven wheel without having the ...
-1
votes
1answer
39 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
vote
2answers
57 views

Need derivation of a formula related to determination of moments of a object about $x$-axis and $y$-axis

I'm given a plate,its density $\rho$ and it is the region bounded by the two curves and on the interval [a,b].I want to find the center of mass of the region below. I’ll first need the mass of ...
0
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1answer
116 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 ...
5
votes
3answers
321 views

The momentum of a swinging sword

Suppose you are faced with a zombie, and the only way to kill it and save yourself is to chop its head off with your sword. However, you are very weak from illness, and can only afford to strike once. ...
0
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2answers
78 views

Torsional Spring and Euler angles

I have a question about the moments generated by torsional springs. Consider an inertial reference frame A and a body fixed reference frame B. The frames are connected by 3 rotational springs acting ...
1
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0answers
33 views

Is the moment-curvature relation for an elastic beam general?

The relationship between the moment and the curvature for an elastic beam is $$M = -EI\kappa$$ Previously, I have only used this with small deflections in static calculations. I am currently working ...
0
votes
1answer
114 views

Downward force applied at center of see saw [closed]

If we are given the length of a see saw of negligible weight, and the weights and distances from the center of the two people on the ends of the see saw, how can we find the downward force being ...
0
votes
1answer
43 views

Determine reactance force of four load cells arranged in two dimensions

I have constructed a "force plate" to reconstruct the location (x,y) of a steady state contact point force f. The system consists of four fixed compression load cells L1, L2, L3, and L4 and a thick ...
3
votes
1answer
83 views

Moments of vibrating string

I have to calculate first 10 moments for vibrating string with damping, but I don't know how to do it. I read about moments and in definition they mention linear system $$x'=Ax+Bu, \qquad y=Cx$$ with ...
0
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1answer
617 views

Calculating Resultant Force and Torque

I'm working on a sandbox game that allows the player to build a spacecraft and attach thrusters in arbitrary locations on the hull of the spacecraft. The game is set completely in 2D. (I'm a ...
0
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0answers
33 views

Why do we consider the application of force as well as bending moment in finding the moments of a beam?

In the standard techniques of beam related problems, solving for moment at any cross section includes counting the torque due to shear force as well as some extra moment, which according to me ...
2
votes
0answers
46 views

Fractional-Order Moments

Commonly seen in physics(and statistics) are the concepts of moments of order zero(mass), one(center of mass), and two(moment of inertia). In statistics a third moment (referred to as skewness) also ...
0
votes
1answer
85 views

Centre of mass, integral

I was answering a question on proving the parallel axis thereom for angular momentum and came across this: $$\int Yy'dm=Y\int y' dm=0$$ Where the position of the center of mass of an object is given ...
1
vote
0answers
198 views

Torque of person on bridge [closed]

Consider a 10 meter bridge that weighs 500 N supported at both ends. A person who weighs 750 N is standing 2 m from the end of the bridge. What are the forces $F_a$, $F_b$ holding the bridgeup at ...
-1
votes
1answer
311 views

How do I know which force to use in moments calculation?

I'm working on some Statics problem, with the method of joints, etc and for all of them, we use sum of moments = 0. However, I'm very confused about which forces I should use to find the sum of ...
3
votes
0answers
214 views

Electrodynamic multipole expansion

I am reading Jackson, Classical Electrodynamics, and I have a question regarding the electrodynamic multipole expansion (with page numbers I refer to the 3rd edition). So on page 409, he gives in ...
1
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0answers
73 views

How many padlocks required to make the Eiffel tower fall over?

Yes the title is an odd question, so I will provide a little background! Recently the sheer amount of padlocks on the Pont d'Art in Paris caused a part of its railing to fall off. Similar padlocks ...
3
votes
1answer
158 views

Why is a dipole moment called a dipole moment?

The General Formula for a moment is the following one: $$ \vec{M} = \vec{r} \times \vec{F}. $$ However the formula for a dipole moment is this one: $$ \vec{p} = Q \vec{d}. $$ How comes this is still ...
-1
votes
1answer
52 views

Initial velocities of a collision [closed]

This is the question: A car of mass 900 kg and a van of mass 1300 kg collide at a crossroads. Investigation into the collision discloses that the car was travelling south east and that the van was ...
1
vote
2answers
285 views

Is the moment of a force the same about any point?

I know that when a body is is equilibrium There is zero resultant force in any direction, i.e. the sum of all the components of all the forces in any direction is zero The sum of the moments about ...
1
vote
3answers
373 views

Why does the moment of force (aka. torque) depend on the perpendicular distance?

Couyld anyone explain how the lecturer concluded that $$(\underline{r_2} - \underline{r_1}) \times \underline{H} = \underline{p} \times \underline{H}$$
1
vote
0answers
44 views

What will be the direction of the force required on the ball to move the ball up the stairs?

Is this diagram correct? The point of force A is at the farthest distance from the fixed centre O ,so the moment arm CD is greater and therefore,maximum torque would be produced.Is my concept ...
0
votes
2answers
671 views

Calculating axle load in cargo container (pics are included)

I'm current developing cargo loader software, but i have a little challenge with calculating load for each axle when a cargo is placed on container. I know that all axles will be affected (the nearest ...
0
votes
1answer
170 views

Moment around a point in a frame

Note: Both diagrams are 2d(they might look 3d because I drew them manually.) I have a prismatic frame that looks like this: I made a section on the half of the first pillar(the red line represents the ...
1
vote
2answers
702 views

How do I find the tension in the cable from this problem? [closed]

I am trying to find the tension of the cable but I don't know what to do.
0
votes
1answer
2k views

Cylinder rolling down slope problem [closed]

A uniform cylinder of mass $m$ and radius $r$ is rolling down a slope of inclination $\theta$. The cylinder rolls without slipping. You may take the acceleration due to gravity to be $g$. At what rate ...
0
votes
1answer
256 views

Damping Coefficient for a Hydraulic-Controlled Door

I am not very good with physics terms, so please treat me as an ignorant. I am trying to calculate a damping coefficient dynamically for a hydraulic-controlled door that opens and closes due to ...
5
votes
1answer
574 views

Do higher-order mass moments have any physical meaning?

The zeroth moment of mass of an object is simply its total mass. The first moment of mass yields an object's center of gravity (after normalization). The second moment of mass yields an object's ...
2
votes
4answers
377 views

Calculating the torque at a point when a motor is stopped?

So, I'm trying to solve for the torque $\tau_A$ of a motor. I have attached a strong stick to the motor, like so: I apply a force $F$ on the stick which stops the motor. The distance from the ...
0
votes
3answers
349 views

Mass equals Moment of inertia when constant density?

I have found equation for moment of inertia $(J)$. I'm calculating $J$ for hemisphere, with rotational axis $Z$. $$ J = \iiint\limits_V r^2 \cdot \rho \cdot dV $$ But if $\rho$ is constant ...
0
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0answers
406 views

Maximum Shear on a Beam - beam with fixed support on one end and hinge on other end

A beam $\displaystyle 3m$ long with fixed support on one end and hinge on the other end is subjected to a uniform load of $10\ kN/m$. What is the maximum shear of this beam? The solution is this one: ...
2
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0answers
181 views

Internal moment in the hull of a pressure vessel

This question is related to the course structural analysis. As part of our exam grade every student has been given different multiple homework assignments which we have to solve. One of the problems ...
5
votes
5answers
5k views

Difference between torque and moment

What is the difference between torque and moment? I would like to see mathematical definitions for both quantities. I also do not prefer definitions like "It is the tendancy..../It is a measure of ...
4
votes
3answers
3k views

First and Second Moment of Mass

I recently came across the definition of the Center of Mass of a system as the point about which the first moment of mass is zero. Further, it defined Moment of Inertia as the second moment of mass. ...
6
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1answer
628 views

Meaning of the word “Moment”?

This question is more of a question about the origin of a physical term moment used in many contexts. My question is about the linguistic or historical meaning of the word "moment". Please don't ...
4
votes
1answer
905 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
votes
1answer
356 views

Using Moments to influence the thickness of beams in structure?

Are moments relevant to the thicknesses of beams in a structure (ie. the larger the moment the thicker the beam)?
5
votes
3answers
652 views

The number of independent variables in the Lagrangian and Hamiltonian methods in Classical Mechanics

It's told in Landau - Classical Mechanics, that in the Hamiltonian method, generalized coordinates $q_j$ and generalized momenta $p_j$ are independent variables of a mechanical system. Anyway, in the ...
1
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0answers
313 views

moment of tennis racket & volley

I've been looking for the relation between moment of a tennis racket and its maneuverability. If I define maneuverability as the easiness to get in position for quick reaction strokes like volleys and ...
3
votes
2answers
1k views

Moment of inertia of a coin

I have a a coin infinitely thin, rotating along the diameter. How to derive the formula for it's moment of inertia passing through the diameter. I was suggested to use the surface density and ...
5
votes
4answers
6k views

Torque vs Moment

I was wondering, why in Newtonian physics torque is called "torque" while in static mechanics they call it "moment"? I prefer by far the term "torque", for not only it sounds strong, but also ...
5
votes
2answers
609 views

Are there 'higher order moments' in physics?

This may be a rather noob question but please let me clarify: I'm struggling to understand the use of the word 'moments' w.r.t., probability distributions. It seems after some research and poking ...
2
votes
2answers
828 views

Intuitive explanation of moments as they relate to center of mass

I would appreciate it if someone could give me an intuitive explanation of moments. I understand that that the center of mass could be thought of as the point which an object would balance on a ...
3
votes
4answers
14k views

What is the difference between a moment and a couple?

In mechanical engineering, the torque due to a couple is given by $\tau = P\times d$, where $\tau$ is the resulting couple, $P~$ is one of the force vectors in the couple and $d$ is the arm of the ...