All Questions
Tagged with definition work
133 questions
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Work force displacement vector doubt
I have known, work is defined as the scalar product of applied force component in the line of the displacement and the displacement, or the product of force component applied in the direction of ...
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-1
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1
answer
55
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Sign convention on thermodynamics - Problem 6.6 Heat and thermodynamics [closed]
I made the problem 6.6 of Heat and thermodynamics by Zemansky. But I have a question with the sign of the final result from section c). If I use $W= P \Delta V$ instead $W= - P \Delta V$, my answer is ...
0
votes
1
answer
129
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Why does $W = \int F\cdot \mathrm{d}s$ rather than $\int s\cdot\mathrm{d}F$ [duplicate]
Conventionally, infinitesimal work is defined as $\delta w = F\cdot ds$ and its integral as the work $$w(P_1 \to P_2) = \int_{P_1}^{P_2} F\cdot ds \tag{1}.$$
The word work, of course, can be assigned ...
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0
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0
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37
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What exactly is voltage? What does it have to do with work? [duplicate]
I am a student and recently learned about electricity. I was reading about voltage. I see that the definition is the work done/charge. I think the work refers to the work done by the electrons as they ...
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4
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2
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996
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Why are there so many different definitions of Work in classical physics by different books and physicists , and which is correct?
Alot of different books , authors and physicists define work differently in classical physics and mechanics.
For example , Halliday & Resnick FUNDAMENTALS OF PHYSICS defines Work as
Work is ...
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1
answer
410
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Clarification Regarding a Possible Typo in David J. Griffiths' Introduction to Electrodynamics
Question:
I am currently reading Introduction to Electrodynamics by David J. Griffiths, and I’ve encountered a point of confusion in Section 2.4 on page 91.
Why is $W=\int_a^b\textbf{F}\cdot d\textbf{...
-2
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1
answer
65
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Work understanding [closed]
I was reading about work. My thoughts are that work is the quantity somewhat related to the total momentum transfer over a distance. This is a way to predict an objects path over another distance. ...
0
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1
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38
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In layman’s language what is the difference between stopping potential and work function?
In layman’s language what is the difference between stopping potential and work function? It feels like both the things mean the same thing, if I am wrong please explain the things to me.
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0
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50
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Why is warming food in the microwave work and not heat? [duplicate]
In Schroeder's An Introduction to Thermal Physics, heat is defined as the "spontaneous flow of energy from one object to another" and work is defined thermodynamically as any other transfer ...
4
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3
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648
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Why isn't work a state function?
I've heard the example, that work is path dependent. But whether I climb a mountain directly or in serpentines, in the end it's the same amount of work, with the one difference that it takes me longer ...
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4
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227
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Kinetic Energy equation: Is $K=\frac12mv^2$ a Definition, or a derived Theorem?
I am trying to understand classical physics as a mathematical model. I will first specify the trail of thoughts that led up to this question. (Please correct me if anything is wrong with the reasoning ...
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1
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2
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96
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Confusion in definition of Potential Energy
Potential energy is defined like this. $ΔP.E=-W_{AB}$. This means that the potential energy at point A minus potential energy at point B should equal the negative of the work done by a conservative ...
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1
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3
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264
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What is kinetic energy?
I am asking these question on a fundamental level please don't go too deep in explaining.
A very basic definition if energy is that It is the capacity to do work, my question is "on what thing ...
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1
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1
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58
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Conditions for a force to be conservative - Does the second condition imply the first? [duplicate]
John Taylor's Classical Mechanics says this...
I was wondering if the second condition already implies the first? I mean, are there situations where the first condition is violated even though the ...
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1
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80
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Is there a non-counterfactual definition of energy? [duplicate]
I have once heard that the definition of energy is "the ability to do work". However, that is a counterfactual definition, because a physical system can have that ability without actually ...
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2
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105
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How can work be a function of position when non-conservative forces don't act the same way at each point?
My textbook and wiki/online articles all claim that work is given by the integral
$$W=\int_\gamma\vec{F}\boldsymbol{\cdot}\text{d}\vec{s}$$
where the $\text{d}\vec{s}$ is some infinitesimal step along ...
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2
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1k
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What is the difference between work done against gravity and work done by gravity?
Work done "BY" a force,from my understanding,is:
•positive when the direction of displacement is same as the direction of force.
•negative when the direction of displacement is opposite to ...
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6
answers
1k
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What exactly is potential energy?
Consider a ball falling from a height $h$. It gains velocity because of the work done by gravity on it. I don't quite understand the role of potential energy here. What does the potential energy ...
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2
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102
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Why is work done = resisting force * displacement? [closed]
Up until now, I have always seen the formula of work done as force * displacement and I thought that this force was applied force but recently in a thermodynamic text while reading about irreversible ...
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2
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104
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Motivation for definition of work [closed]
Why do we take the dot product in the work energy theorem? Consider the integral
$$\int\vert\vec F\vert\vert d\vec r\vert$$
Why don't we define this to be work done for example, instead of $\int\vec F\...
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1
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88
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${}$Conservative and Non-Conservative Forces
For work done by conservative forces ($W = F.S$), we consider $S$ as the displacement and not the actual path travelled. However for non conservative forces we consider the total path length and not ...
1
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4
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282
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Definition of Heat and the requirement of a different temperature - Zemansky
In Zemansky's "Heat and Thermodynamics", the concept of thermodynamic heat is defined as:
$$ Q = \Delta U - W_{i \to f}^{dia}$$
where $\Delta U$ is the change in internal energy between the ...
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1
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2
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705
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Why does small work done mean $dw=f.ds$ and why not $dw=df.ds$ and why not $dw=s.df$? [duplicate]
Work, power and energy questions.
Why does small work done mean:
$$dw=f.ds$$
and why not:
$$dw=df.ds$$
and why not:
$$dw=s.df \ \ ?$$
2
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4
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115
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Work in thermodynamics and work in mechanics
work in mechanics
$w=\vec{f} \cdot \vec{s}$
work in thermodynamics
$w=-p \Delta v$
I don't understand why $ \vec{f} \cdot \vec{s}= -p \Delta v$ ?
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1
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2
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222
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Work done by non-continuous force
How work done is really understood?
I know that $W=F\cdot d$. I am interested in the meaning of force here i.e.
Is it a continuous force applied till displacement? like the case of pulling trolley ...
- 101
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3
answers
64
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Definition on type of work [closed]
A man carries a bag hanging it in his hand and he moves horizontally. The bag does not move up or down. What is the work done on the bag? The man gets tired after some time of the movement. Why?
1
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4
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972
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What is constant in an isobaric process, internal pressure or external pressure?
I was taking a course in thermodynamics, where the instructor started to derive the formula for work in case of isobaric process for an ideal gas
It stated W = -∫ P_ext dV
And then equated it with -∫...
0
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1
answer
711
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Formula for work done for both conservative and non-conservative force are different?
We know that the formula for Work Done by an constant force is
W.D = Force x displacement x (cosine of angle between force and displacement).
Situation: A mass m travels 10 meters towards +ve axis ...
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10
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6k
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What is a joule? I find the definition confusing
This is the definition on Wikipedia:
It is equal to the amount of work done when a force of 1 newton displaces a body through a distance of 1 metre in the direction of
the force applied.
I take that ...
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6
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4
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859
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Potential energy definition
I am too much confused about the definition of potential energy. I am giving two different definitions below:
The negative of work done by conservative force to bring a mass from infinity to the ...
user325381
0
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1
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47
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How to know what force to plug in for work?
Suppose I have a positive charge $+Q$ at some point, and I want to see how much work I need to do to bring a negative charge $-q$ to a distance $r$ from that point. The direct calculation is done via ...
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1
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3
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515
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In reversible process, why define $\delta W=-PdV$ instead of $\delta W=-VdP$?
For a reversible process, it is assumed that the external pressure $P_{ext}$ is infinitesimally different from internal pressure $P_{int}$.
So in reversible process, I can have $~P_{int}=P(V,T)~$ but ...
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4
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3
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866
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How can an object do work?
I read in many sites that the concept of mechanical energy is the ability of an object to do work, but how can an object do work? Isn't it rather the force applied to that object the one that produces ...
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0
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168
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Is it sufficient to define energy as "ability to do work"? [duplicate]
Energy is the ability to do work. If an object possesses energy it possesses the ability to do work.
This is how energy is usually defined . This definition fits mechanical energy very well .
But I ...
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2
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What is the general formula of work in terms of pressure and volume?
I've seen work often represented by the formula $$W = PΔV$$
But there are also other formulas, which represent different types of work. For example,
Non Flow Work
$$ W =\int_{1}^{2} PdV $$
Steady ...
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1
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3
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115
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Clarification on the displacement in the definition of Work
I'd like to ask a question about work. The definition of work gives us a way to calculate the work done by a force along a path but in practice it's not always clear what path to take in consideration....
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4
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2
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1k
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Proving if a force is conservative and non-conservative
recently I have studied conservative forces and non-conservative forces in halliday book and while doing some exercise I saw some questions asking for proving if a force is conservative so after doing ...
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3
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5
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946
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Positive and negative Work, question
I have a question on the sign of the Work quantity. My understanding follows:
$$
W = \int_C \vec F \cdot d \vec S
$$
$$
W = -\Delta U, \qquad -W = \Delta U
$$
For direction and sign:
$$(-F, dx) = \...
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2
answers
403
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What does potential energy really mean?
I have a lot of doubts regarding the potential energy definitions
First of all,I would try to express my Understandings(they might be wrong)regarding the issue
I was told that if Work done on a body ...
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1
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2
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129
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Correlation between conservative forces, non-conservative forces and potential energy
So I recently learned the definition of conservative forces, and how the work done by such forces depends only on the initial and final position of the particle but then we learnt about definition of ...
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11
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Are energy and work the same thing?
When revising formulas the other day I came across something:
Energy = power × time
If we substitute power we get
Energy = work/time × time
The time cancels out. So is work equal to energy?
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2
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251
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Why is work done force times displacement? [duplicate]
Why is work done the product of force and displacement? Why not force and time?
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4
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4k
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Why do we multiply $\cos θ$ in the formula for work? [duplicate]
I know that the formula for work, $W = FS\cos\theta$, where $F$ is the applied force, $S$ is the displacement of the object and $\theta$ is the angle between the applied force and the displacement of ...
0
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1
answer
127
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Is the definition of Work done by Torque a general result?
I was going through this post.
In the post the person who asked the question mentioned a statement:
"Lastly, I am emphasizing that I'm am NOT saying that torque is incorrect, only that the work ...
- 1,588
1
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3
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332
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Is the $d$ in $W=F*d$ displacement or distance?
My textbooks say that work=force times displacement but when I was considering conservative and non-conservative forces I got a bit confused. I know that the work done by non-conservative forces onto ...
0
votes
3
answers
2k
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Work done on a frictionless surface
Imagine that we apply a force $F$ on a frictionless surface to move a body by a distance $d$. (The body starts at rest and is stopped after moving a distance $d$.)
Is the work done $F d$?
But from ...
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1
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0
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39
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Why is work done equal to force×displacement? [duplicate]
I have understood that work done depends on force and displacement but I have not understood that why does the product of these two gives work done and not multiplied by some constants or raised to ...
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1
answer
61
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Is energy, as we know it, "persistent"? [duplicate]
Suppose I raise a ball (with my hand) to some height. I am doing some work against gravity and storing potential energy in the ball.
However, once I loosen my grip, or just sweep my hand away from ...
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3
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4
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411
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How is the definition of work motivated?
For most dynamical variables in classical physics, I can understand how one may have decided to introduce them as a result of some "incompleteness" in Newton's laws of motion. For example:
...
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7
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662
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What comes first: Work or kinetic energy?
Suppose we have a body initially at rest. Now a force ($F$) is continuously applied on it and it gets displaced by some distance $x$.
My tutor said that from work energy theorem it gains kinetic ...
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