Questions tagged [work]
The product of the force on an object and the displacement the object undergoes along the direction of the force.
3,243 questions
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Where is the increased mass reserved based on Einstein's mass-energy equation?
Assume a huge parallel-plate capacitor with plates located at an infinite distance away from each other. If we tend to move a positively charged object ($+q$) with a rest mass of $m$ against the ...
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Does the electric potential energy of a positively-charged particle vary directly with its distance from a charged particle or surface?
Current high school AP Physics II student here, so apologies if this question comes off as unlearned.
I'm trying to learn about electric potential in my class, but I realize I still don't understand ...
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Why am I getting Work done as negative in bringing a positive charge near another positive charge? [duplicate]
Let us consider a charge $Q>0$ at origin. Let $P(r,0)$ where $r>0$ be on $X$ axis.Consider a point $M(x,0),\:x>r$ from which we have to move a charge $q>0$ towards point $P$.
Now I am the ...
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Why does Callen not take into account the change in entropy of the reversible work source?
I am reading the second edition of Callen's Thermodynamics and in particular about the maximum work theorem which essentially states that a process which produces work and heat produces maximum work ...
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Ambiguity in work-energy theorem for a system
in this question if I have to find max compression in spring then if I consider both block and spring as system and then apply work energy theorem then as I have written above that spring force is ...
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What does it mean for work to be done ON a system?
I have been reading different literature on thermodynamics for a course at university, and of course, the idea of work being done ON a system is very central. What is rather seldom explained, perhaps ...
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Definition of conservative forces [closed]
Can we say that a conservative force is a force whose direction doesn't change with change in direction of the velocity (of the body)? For example the direction of frictional force changes with change ...
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Is the formula $\tfrac12kx^2$ valid even for a massive spring? [closed]
Problem (University Physics, 15th ed. by Young & Freedman challenge problem 6.93):
We usually ignore the kinetic energy of the moving coils of a spring, but let's try to get a reasonable ...
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Work done by a body in a relative motion
I was working on the problem detailed below and found a "contradiction" between the required force balance condition and the virtual work method. I believe the resolution requires a more ...
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Conservative Force [closed]
If the gravitational force is a conservative force, then its work done will be the same in all the paths followed. But If we move a mass in scalene triangle, the work done from A to C is not the same ...
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Why does internal energy end up higher in an irreversible adiabatic process, even though the work done is less?
I am having a hard time understanding irreversibility in thermodynamic processes, more specifically, the situation my textbook presented. In an adiabatic expansion with a weightless piston held in ...
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Negative sign in Voltage definition confusion
This part from Electromagnetic - Field Theory Fundamentals (Guru) has always confused me:
This part makes sense, it's just the work done by the field:
$
dW_e = {\bf \vec F} \cdot \vec {dl} = q {\bf \...
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Whose work to be considered in first law if the process is non-quasistatic? Work done by the gas (system) or the external agent's?
Under quasi-static conditions, work done by the system and external agent (on the system) are equal and opposite.
In Chemistry textbooks, first law is generally mathematically expressed as:
$\text{d}U ...
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Why is no work done in bringing a charge from the surface of a charged spherical conductor to the inside?
When we bring an external charge and try to get it into the inside of a charged spherical conductor, there should be some work done to bring it on the inside. Naturally, a charge would not go to the ...
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Problem on a solution of a work required to pull a hanging cable [closed]
In a calculus book that I'm reading, there's an example of pulling a linear homogeneous cable that's hanged on the top of a building as follows:
In part b, the author divides the work into two parts:
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If a object starts from rest and stops at rest doesn't matter how much displacement it travelled net work done is 0, but how can it be possible?
As we know total work done is equals to change in kinetic energy. But if initial and final velocity of body is same, the total work done is always zero.
How can this kind of situation exist?
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Conceptual unclarity in work-energy theorem (non-conservative forces)
A block of mass $m$ is attached with a massless spring of force constant $k$. The block is placed over a rough inclined surface for which the coefficient of friction is $μ=3/4$. The minimum value of $...
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Interpreting the sign of chemical work in a $(T,\mu)$ cycle
I'm having trouble understanding the sign convention for chemical work in a thermodynamic cycle represented in the $(T, \mu)$ plane, where $\mu$ is the chemical potential and $T$ the temperature. The ...
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What is doing work in a system with a stationary electron where the field increases?
Imagine a system with a stationary electron, where the value of field it's in is changing. Now the potential energy of electron should also change, but the electron is stationary and work is defined ...
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Where does the energy from your muscles go when you lift a rock in a rocket?
My friends and I have been struggling with a seemingly simple physics problem. The question is about what happens to the energy in various different situations when you lift a rock onto a shelf and ...
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Bicycle Oberth effect
I know of the Oberth effect, which states that it is more efficient to put in work at high velocity. It is usually applied to orbital mechanics, but the explanations I saw only talk about kinetic and ...
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Rotational Work and Energy
Question:
In rotational dynamics, we often use the formula:
$$
W = \tau \cdot \Delta\theta
$$
to calculate work, where $\tau$ is the torque and $\Delta\theta$ is the angular displacement.
My question ...
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What is the amount of work that the floor does when you jump if the floor is compressive?
If the floor isn't compressive and the Earth's mass is too big to consider, the floor does not do work on you. What if it's like the real world, where the floor compresses a little and the Earth moves ...
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Free expansion of a van der Waals gas [duplicate]
Today I came across a question that said that in the free expansion of a van der Waals gas the temperature of the gas decreases but I can't seem to understand this because, since the system is ...
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Inelastic collision after sticking with massless spring?
Is energy lost when a block falls on a vertical and a relaxed massless spring from a height h above it from no initial velocity and 'sticks' to it doing SHM. I feel it should be, since the collision ...
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