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Questions tagged [work]

The product of the force on an object and the displacement the object undergoes along the direction of the force.

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Is the given force conservative? [closed]

I've attached an image in which a question can be seen. I've successfully solved the problem and the answer is zero. However, I seek if the given force is conservative or non-conservative. I think it ...
Apoorva Shukla's user avatar
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2 answers
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Does doing work on system increase or decrease its internal energy?

I am currently reading about the 1st law of thermodynamics, from the book "A Hot Story" by G. Venkataraman. While discussing the law, the author tells that when we do work on the system, its ...
Anindita Sarkar's user avatar
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Force applied by hand, force applied by the spring and the corresponding work done

Consider a block of mass $m$ is attached to a massless spring of force constant $k$. If the spring is pulled by hand so that it stretches by an amount $x$, its potential energy increases from zero to $...
Solidification's user avatar
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Drawbacks of Quasi-Static process for lifting a block

Definition of Quasi-static: A quasi-static process is a thermodynamic or mechanical process that occurs very slowly, allowing the system to remain in a state of equilibrium at all times. While ...
Akhilesh G's user avatar
1 vote
1 answer
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Can siphons improve the efficiency of hydroelectric dams?

Suppose we have built a hydroelectric dam where the water inlet is 100m above the outlet. We can now use the gravitational potential of the water to spin a turbine. However, suppose we install a ...
orlp's user avatar
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Work Done by kinetic friction in Circular Motion

We know when an object is moving in a circular motion on a rough horizontal surface, direction of kinetic friction is constantly. Thus, fto calculate the work doen by friction, we need to use ...
Akhilesh G's user avatar
1 vote
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Potential of Monolayer Graphene as a High-Precision Cutting Material

"I am exploring the use of monolayer graphene as a cutting material for high-precision applications. We know that graphene has exceptional mechanical properties, such as high strength and ...
Davi Diniz's user avatar
3 votes
2 answers
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Areas with anti-parallel gravity in classical physics

I cannot indicate an error in the following reasoning if it is done in the framework of classical physics. Let's make the imaginary setup with two wedges and the ball, when the gravity in the left ...
Artem's user avatar
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Energy Transfer and Work in Action-Reaction Forces [closed]

simple but confusing for me. I hope this question doesn't close or disappear. Questions continue to arise about work and energy. Situation Description A and B exert forces on each other and do work. ...
NOH WHIREA's user avatar
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Why Does Every Member of the Ensemble Perform Work Equal to the Change in Free Energy During a Quasiequilibrium Process?

I'm studying Jarzynski's 1997 paper on the Jarzynski Equality. In the second part of the proof (from equation (9) to equation (10) in the paper), Jarzynski considers the following process: considering ...
Luessiaw's user avatar
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Thermodynamics exercise on transformations

An exercise in my book states the following: n = 0.42 moles of an ideal biatomic gas are stored in an adiabatic cylinder with volume $V = 10^{-2} \text{ m}^3$, with an initial pressure equal to one ...
NICOLA TROMBINI's user avatar
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Voltage: work to move a charge, or difference of electric potential?

Let's say I have a single positive charge inside of an electrostatic field. I want to move this charge from point A to point B and determine the voltage between the two points. Points A and B are the ...
oh no's user avatar
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1 answer
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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.
User_5117's user avatar
1 vote
4 answers
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Why is work done by force $+mgh$ in the situation of throwing something up?

If there is a particle at point A(at rest) and a force moves it to point B(Above point A vertically)(final velocity = 0 at this point), the work done by gravity is $-mgh$. This I understand as the ...
Gaurav Batra's user avatar
-3 votes
1 answer
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Strange calculus involved in work and power [closed]

If force is given by $$F(t)= 3t^2i + t^3j$$ and velocity is $$v(t)= 5t^2i + 2tj$$ then what is work done in time $t$. Now we can obtain power by their dot product $F.v$ and then integrate power to get ...
Harjot Dhillon's user avatar
1 vote
2 answers
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Work performed by hydrostatic pressure

One should be able to show mathematically that the hydrostatic work done by an environment on an object undergoing a volume change $\Delta v$ should be $p \Delta v$, where $p$ is the (constant) ...
creillyucla's user avatar
1 vote
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Work done by Lorentz force

our teacher asked a conceptual question. Let two infinite straight wires carrying current in the same direction be suspended in vacuum near each other. the wires tend to get attracted due to the ...
Ajitesh Sophat's user avatar
1 vote
1 answer
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Why the work done by surrounding on the piston is same as average work done by surrounding on the gas inside the cylinder? [closed]

In thermodynamics when we derive the formula for work done by the surrounding on the gas, we actually derive the formula for work done by the surrounding on the piston and say that let the surrounding ...
Virender Bhardwaj's user avatar
1 vote
3 answers
106 views

The conservative force [closed]

I read about the definition of the curl. It's the measure of the rotation of the vector field around a specific point I understand this, but I would like to know what does the "curl of the ...
Dirac-04's user avatar
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1 answer
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Where am I wrong in proving that force perpendicular to motion increases speed and kinetic energy? [closed]

Lets think of a helicopter flying at some height $h$. It throws a food packet to a person on the ground from air. Let's neglect the air drag. The food packet is thrown only with some velocity $v_x$ in ...
Gaurav Batra's user avatar
3 votes
5 answers
950 views

Is the work I do on the object always equal in magnitude but opposite in sign to the work the object does on me?

According to the definition of work, the work I do on an object is equal to the force I apply to the object multiplied by the distance the object moves. By Newton's third law, the reaction force (F21) ...
NOH WHIREA's user avatar
-1 votes
0 answers
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Interpretation of Enthalpy when there is no $pV$ work done [duplicate]

Enthalpy tends to be defined as terms of a pressure volume work. I am looking at a one dimensional system where there is no $pV$ work and trying to get an intuition of enthalpy in this context. Can ...
Thomas Hayes's user avatar
0 votes
3 answers
70 views

How is the expression for work in this problem derived?

In this solution to the problem I found, the work expression comes out to be the force times $d$, the difference in distances from the collar to the force origin at positions A an B. I can't for the ...
CarolusRix's user avatar
1 vote
1 answer
63 views

Vanishing virtual work done by non-holonomic constraints

I was reading classical mechanics by NC Rana. I was reading a topic on vanishing virtual work done due to constraint forces. How do you prove that the virtual work done by non-holonomic constraint ...
Aaron Nelson's user avatar
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2 answers
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Do we have to provide energy to move electrons in an electric field?

In the positive and negative terminal of a battery, there is potential difference due to the accumulation of charges in their respective terminal, so it created a potential difference, and if we ...
Nishesh Tyagi's user avatar
1 vote
2 answers
79 views

Why is work done by normal force 0 here?

In solving this problem from Kleppner and Kolenkow, the (total) work done by the reaction force b/w the cube and the large block is taken to be 0 and I cannot seem to rationalise this. Clearly, the &...
Vulgar Mechanick's user avatar
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2 answers
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Is it possible that work is being done on an object, it's kinetic energy doesn't changes and still the body is transferred from one point to another?

Recently, I read a book about Electrostatics which stated that "Electrostatic Potential at a point is defined as the work done to move a unit charge from a reference point (generally taken as ...
Kunal Prajapat's user avatar
1 vote
2 answers
77 views

Rigorous definition of potential energy of a system

In the mechanics textbook by Kleppner and Kolenkow, the concept of potential energy is introduced by considering the behaviour of particle under the action of a force $\vec{F}(\vec{r})$ that depends ...
Vulgar Mechanick's user avatar
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2 answers
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Work done in a system of masses

Let's say we have this system: Why is the work $$W_{tot} = mgh - F_f h$$ where $F_fh$ is the work done by friction? I don't know why this happens. My guess would be to consider both blocks as one and ...
samsamradas's user avatar
1 vote
2 answers
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I am confused about potential energy and work done by a force [closed]

Potential energy is the energy contained in a body due to its position. But I don't understand it because when object falls, PE= mgh and work done by gravity, is - mgh. So what is the difference other ...
android's user avatar
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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 ...
PineappleThursday's user avatar
5 votes
3 answers
2k views

When does the magnetic field do work?

When particles are affected by a magnetic force and move in a circular motion, no work is done. Why is this the case? Is it because the force is perpendicular? However, when a conductor loop enters or ...
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2 votes
1 answer
92 views

Work Done and Direction with frictional forces

This might be a dumb question, but if work done is equal to the force exerted on an object in the direction of motion (so W = F*S), then how come frictional forces do work on an object. For example, ...
WhoAmIWhyAmIHere's user avatar
0 votes
3 answers
49 views

How is electric potential the work done on a unit charge?

I recently read that electric potential at a point is defined as work done in bringing a positive unit charge from infinity (or any other reference point) to that point. How can electric potential be ...
Anvi Mahajan's user avatar
0 votes
1 answer
91 views

Work-energy theorem confusion [closed]

I know that: $$W = \Delta KE$$ and that: $$ME = KE + PE$$ I got confused about one problem my teacher did why did he use: $$W = \Delta ME $$ The problem in question is shown below: Your cat, the ...
samsamradas's user avatar
1 vote
3 answers
56 views

Under what circumstances the work done by an external force gets stored as potential energy?

Consider earth and a block as a system. The block is accelerating downward under gravity. Now I apply a force against gravity which is less than the force of gravity. Would the work done against ...
Anvi Mahajan's user avatar
0 votes
2 answers
113 views

Paradox? Why does energy conservation appear to be violated in this simple geared system?

While answering a question about gears and levers, I found I could not get the work in to equal the work out in this simple gear system illustrated below: The gears are set up to replicate a lever, ...
KDP's user avatar
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1 vote
3 answers
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What is the actual meaning of $dx$ in $W=-F.dx $, in work in thermodynamics?

what I want to ask is that the $dx$ in that formula is the displacement of piston or the displacement of the center of mass of the gas. also is there any situation where this clarity is useful.
Ujjwal's user avatar
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1 answer
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Deriving expression for gravitational potential energy around a mass, $M$, using vectors

(I think my question will be somewhat related to this one: Deriving gravitational potential energy using vectors .) I know the change in the potential energy associated with a conservative force, $\...
Anis Manuchehri-Ramirez's user avatar
10 votes
2 answers
915 views

Is work done by a charged particle not gauge invariant?

Work done by a charged point particle with charge $q$ in an external electric field derived from a scalar potential $\phi$ is given by $$W=q \phi.$$ Even if we add a magnetic field the definition ...
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0 votes
3 answers
84 views

Why does my potential energy decrease when lifting a book?

I was reading morin's intro to mechanics book, and i reached the point where he was discussing work potential energy equivalence, which i find very confusing right now... basically we are analysing me ...
Aditya_math's user avatar
0 votes
1 answer
42 views

Static friction, no work

Imagine a ball rolling without slipping on the floor. Then the force of static friction has non-zero torque, so why it doesn't change the overall energy of the ball?
Piotr H's user avatar
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1 vote
4 answers
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Physical meaning of negative work

I have a simple question here. I've been learning quite a bit about electrodynamics and solving some problems. However, I'm stumbling on a problem: I always get the correct expression of work but have ...
AhmedSahraoui's user avatar
1 vote
0 answers
37 views

Why doesn't net work equation take the change in potential energy into account? [duplicate]

I know that $$\text{net work} = \text{work done by conservative forces} + \text{work done by non-conservative forces}.$$ and $$\begin{split}\text{net work} & = \text{change in kinetic energy} + \...
Rohan Rajasekar's user avatar
-4 votes
1 answer
97 views

Does every object have an infinite amount of energy? [duplicate]

If energy is defined as the capacity to do work, and the formula for work is force times displacement, if we place an object on a frictionless surface and apply any amount of force to said object, the ...
ryangosling's user avatar
0 votes
2 answers
44 views

How do we write the potential difference between the final and initial points?

If you want to find the potential difference between point A and point B, the potential difference is written: $$ V_{ab}= V_{a} - V_{b} $$ or $$ V_{ab}= V_{b} - V_{a} $$ AND is work the same thing? I ...
J.R's user avatar
  • 103
0 votes
2 answers
55 views

Piston cylinder question [duplicate]

I have a simple question, but it confuses me a lot. Suppose we have a piston-cylinder device that is being heated, say, at the rate of Q_dot. All other faces can be assumed to be adiabatic. The ...
Ankush's user avatar
  • 11
2 votes
1 answer
120 views

Where will be the equilibrium position for the piston?

A piston can slide without friction inside a horizontal cylindrical vessel, which contains an ideal mono-atomic gas. The piston and the inner surface of the cylinder are coated with a thin layer of a ...
Yash Shrivastava's user avatar
0 votes
1 answer
37 views

Does altering particle direction constitute work?

Given a moving charged particle entering magnetic field and therefore changing direction as a result, yet still the energy of the particle remains the same. Did the magnetic field perform work that ...
Andrei Bronnikov's user avatar
0 votes
5 answers
139 views

Why $VdP$ term omitted in isothermal Work?

Context: I'm asking about classical thermodynamics, that is "ideal gas", closed system, reversible processes etc. Why is the $VdP$ term omitted in calculation of work during isothermal ...
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