What is Virtual work: Definition and 69 Discussions
In mechanics, virtual work arises in the application of the principle of least action to the study of forces and movement of a mechanical system. The work of a force acting on a particle as it moves along a displacement is different for different displacements. Among all the possible displacements that a particle may follow, called virtual displacements, one will minimize the action. This displacement is therefore the displacement followed by the particle according to the principle of least action. The work of a force on a particle along a virtual displacement is known as the virtual work.
Historically, virtual work and the associated calculus of variations were formulated to analyze systems of rigid bodies, but they have also been developed for the study of the mechanics of deformable bodies.
I refer to the figure:
Is it true that affixing the rope at the point A isn't the same of affixing it at the point B? (I consider the rotation movement around O since the disk is rolling, and so the radius of rotation is different in the two cases)
I'm sorry because my english is not very...
Homework Statement
Homework Equations
?
The Attempt at a Solution
a) y=2Lcos(θ)
x=2Lsin(θ)
b)
I haven't started the next question as I want to make sure the active force diagram is correct first..
If somebody could just check the diagram and help me with where I'm going...
PROBLEM 1
Homework Statement
The frame in the figure is supported by a hinge in A and a roller in G. It is loaded by a couple = 14 kN*m in B, a force = 12 kN in D and a distributed force = 4 kN/m on section EG. = 1.4 m.
Calculate the normal force in C. Use the correct signs...
Hi,
I've been reading chapter 4 in the Feynman Lectures on the conservation of energy and I've bought a book off amazon called Exercises in Introductory Physics which accompanies the series. Having looked at some of the questions I feel well out of my depth because essentially I haven't ever...
Hi all,
I am having trouble understanding Virtual displacements and related ideas and would appreciate your help!
Let's say we have a simple pendulum and we take a snapshot of this system at some instant of time :
A 'virtual displacement' is said to be :
- consistent with the constraints on...
Hi everyone, I'm studying applied dynamics for college.
I have a simple question and then a more importante question:
F=dq/dt=ma
(torque)T=dL/dt
What do you call these equations, Newton-euler equations?
I use these equations all the time to relate forces and torques with motion, in certain...
Hello
Just had a quick question for a structures class. When attempting a problem, what's the main difference between applying PVW and PMPE? What would classify a problem in using one over the other?
Thanks
I could not understand the Principle of virtual work.
Suppose we have two (x,y,t) [at two different points].By principle of least action we will get a trajectory such that it minimize lagrangian.
Does the principle of virtual work say that it will vary the path a little but having the same...
rigorous statement of virtual work principle??
in the texts on mechanics the virtual work principle is always stated in 'infitesimal form'.
is there a "proper" way to write the principle of virtual work in which we don't leave it in terms of INFINITESIMALS.
i want to throughly understand the principle of virtual work. why this principle was invented?
"sum of work done by forces is zero". such a definition is very vague for me. can anyone explain?
Homework Statement
anyone guide me step by step how to use virtual work method to calculate all reactions on this beam?
thanks
Homework Equations
The Attempt at a Solution
using the principal of virtual work, find the reactions of the following structure
as far as i know, to solve using virtual work i take the statically determinate structure and release one of the support reactions making it indeterminate (1st degree),
after picking my brain with the...
Homework Statement
Derive the equation used for calculating the deflection of a beam at some arbitrary point.
Because I haven't seen anything like this on the web or in textbooks, I am asking for some feedback.
Homework Equations
v_{k} = \int\frac{\delta M(x)M(x)}{EI} dx
The Attempt...
Hi All!
I am new on here so I hope you quality people can help me out:)
I have this question and it asks me to solve it using Virtual Work? What is that and how do I apply it to this question:
"A slender rod of length L is attached to a collar at B and rests on a portion of a circular...
In reading Feynman's "Lectures on Physics", volume 2 I have a question and have included a scan of a small section from the book.
Feynman was a big fan of using the Principle of Virtual Work, but his explanation, as least insofar as how he used it is wanting, at least for me.
The attached...
How do you go about solving an indeterminate beam for various deflections by virtual work? I'm kind of at a loss right now and can't proceed on my homework. I've attached a picture showing the problem I'm confused on - I don't know how to go about modeling the virtual model so I can find the...
Homework Statement
Im having real trouble with drawing diagrams for virtual work. Can someone please, please help me!
We were asked, in the diagram i posted, to find 1)vertical reaction at F, 2) all reactions at A, 3) bending moment and shear force at B using virtual work.
i think i...
I was just reading the Feynman Lectures on Physics when Feynman discussed virtual work. Unfortunately, I found his explanation somewhat confusing.
The following are the three examples Feynman uses in order to illustrate the principle of virtual work.
1.
2.
3.
I'm trying to...