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

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Dealing with negative work

Dumb question, I'm working with vector fields right now, and one question on here tells me to assume an object can take on three paths from a to b. (paths not listed here) for times in [0,1] Now ...
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53 views

How work theoretically is zero, when person did do work while covering a distance then returning it?

$W = Fd$, meaning if a body moved a distance, say $3 m$, and returns, its distance will be zero and work will be zero. I do understand it mathematically and graphically but can someone explain it to ...
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60 views

How this formula for work follows from the definition?

If a particle moves along a path $\gamma : I\subset \mathbb{R}\to \mathbb{R}^3$ then the work done by a force $\mathbf{F}$ is defined by $$W = \int_{\gamma} \mathbf{F} = ...
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34 views

Does the effect change if a continuing and constant force acts upon a mass?

If a continuing and constant force $F$ acts upon a body with the mass $m$, does the power (work per unit time) increase over time? It would mean that the converted energy per time unit increases. Is ...
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106 views

Work and Free Body Diagrams

I am a bit confused with how to find work when there is a free body diagram. I am trying to work out this problem, and in it a box is being pulled at a constant speed by a rope at a constant angle ...
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63 views

Does inducing charge on a grounded conductor do work?

Imagine a grounded conductor as an plane of infinite area. If I bring a charge to a close proximity to the plane, it induces some charge distribution on the conductor. The question is: is any work ...
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229 views

Why does the coefficient of performance need to be calculated with $W + Q$?

How much work must a heat pump with a COP of 2.50 do in order to extract 1.00 MJ of thermal energy from the outdoors (the cold reservoir)? The first formula that came into my mind after reading ...
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467 views

Work done by a conservative force

Wikipedia: A conservative force is a force with the property that the work done in moving a particle between two points is independent of the taken path. Equivalently, if a particle travels in a ...
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Does an opposing force cause loss/ waste of energy?

I found this answer by John Rennie (in the question you see the train on a track): when the train moves a distance $d$ the work done on the train is $Fd\cos\theta$. It's certainly true that ...
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43 views

A captious work problem: same paths but same forces?

A man jumps onto a chair. A man climbs onto a chair by putting a leg first and then the other. In both cases, the work has been the same. TRUE or FALSE...? Spoiler!: The path is the same, so the ...
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1answer
128 views

Potential Energy of Springs and Gravity, and Work of a force

I am currently really stuck on this problem and I am not sure how to actually solve it, I think I can reason it out logically but I do not know how to show it. Here it is and under I will show what I ...
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37 views

Change in work done by dipole

How would you explain the intuition behind the equation $dW = -\tau d\phi$ for an electric dipole?
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Thermodynamics and Internal Energy

I've been working on this problem for quite some time trying to figure out the most efficient way of answering it, So here goes the problem: There is a container, containing a monoatomic gas with ...
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Connection: Work on dipole <-> optical absorption

If I consider a two-level system with a ground and an excited state, I can compute the instantaneous rate at which work is being done on the dipole $\mu(t)$ by an electric field $E(t)$: $\dot{W} = ...
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0answers
48 views

Why is no work done by magnetic forces in a uniform B and E field (perpendicular to one another)?

Say $B$ points in the $x$ direction, and $E$ points in the $z$ direction. Assuming a charged particle begins at rest at the origin, its motion will be a cycloid that progresses indefinitely in the ...
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0answers
49 views

Is work done on a fluid in a communicating vessel necessarily equal to work done by the fluid inside it?

During the explanation of Pascal's law the argument that work done by a force to move the fluid inside communicating vessel is equal to the work done by the fluid at the other end of the vessel was ...
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0answers
66 views

Restrained expansion of a piston/cylinder

Suppose an ideal gas in a piston cylinder has some initial pressure $p_1$, volume $V_1$, and temperature $T_1$. A pin, which holds the piston in place, is suddenly removed, and the gas quickly ...
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0answers
134 views

How to solve state parameters using these givens for an ideal gas?

In a thermodynamic turbine using air as an ideal gas, given that you have a known inlet temperature value $T_i$, a known exit pressure value $P_e$, a known inlet and exit velocity $V_i$ and $V_e$, a ...
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100 views

Problem in average height

Let, diameter of cylinder hole of height 30m and diameter 2m filled with water. In a book, when author tried to find out the power for lifting all of the water then he used average height. why is ...
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22 views

How is the Joule normalised?

Apologies if this question is a duplicate, I tried searching for this question both on Google and here, but was unable to find an answer. A Joule is defined in various ways, some of them being: ...
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0answers
39 views

How to tell direction of work

I think of direction of work as relative to direction of motion, but I got a question of a parabolic ball throw asking the direction work done by gravity and friction over the entire parabola. Since ...
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0answers
14 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 ...
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0answers
67 views

Work done by heating a balloon with $H_2$ ideal gas

I have a difficulty treating this problem. Could you help me to understand the questions, please (I did my attempt)? Problem Consider a spherical balloon filled with $H_2$ gas. Due to a ...
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29 views

Muscular energy transformations with regards to gravity

Maybe this has more to do with biology than I know, but I have been wondering just what kind of energy muscles use and convert when lifting a weight off the ground or lowering a weight back to the ...
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67 views

Work to Create a Vacuum

I'm trying to determine the amount of work required (in Joules) to create a vacuum of a certain pressure in a tube. A pneumatic cylinder will be used to remove the air from the tube to create the ...
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51 views

Charge Image Problem: Work done on charges on the plate

Assume there is an infinite grounded conducting plane in the $xy$-plane. Assume also that a point charge is being brought slowly from $z=\infty$ to $z=z_0$, slowly enough that the problem is treated ...
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50 views

Work done on an object from different frames

Consider this situation: A car is moving on a road and applies brakes. The road exerts a force $F$ on the car, due to which the car stops in $S$ meters. Clearly, the work done by the road on the car ...
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63 views

How does pressurized gas constantly push?

If a gas, such as hydrogen, is pressurized into an air tight container, a force in terms of pascals (or whatever unit you want to use) is exerted, correct? That is what pushes against every surface ...
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342 views

Work done by rolling vs skidding friction force

Two identical bicycles having equal weight riders are traveling along a level road adjacent to each other with the same non-zero velocity. Bike A, (the "skidder"), applies the rear brake strongly ...
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130 views

Collision of two deformable bodies - limitation of work-energy theorem

I am attempting to model the impact of a deformable body (clean, dry sand characterized as a continuous fluid) with flexible diaphragm (in this case a sheet of rubber). Assuming that this is a closed ...