# 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 definition of work related to the nature of the fundamental interactions?

I am having troubles trying to understand why is work defined as it is. So, I know how work is defined: $W = \vec{F}\cdot{}\vec{d}$ (F is the force, d the displacement) and I am okay with it. This, ...
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### Non-Work energy conversion

Are there any conversions of energy that are not considered work, (energy change with a force and displacement)? For example heat transfer does not convert the form of energy, can something such as ...
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### What is the work done by friction on a body from the perspective of different observers using the formula $-μmgl$?

Consider two observers moving with respect to each other at a speed $v$ along a straight line. They observe a block of mass $m$ moving a distance $l$ on a rough surface. The change in KE of the block ...
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### Concept of work [closed]

How was the concept of work and energy invented in physics? What is the actual idea behind work and energy? Why are distance and force specifically used to define work, why not time instead of ...
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### The work done by tension and normal forces are conservative or non-conservative? Give reasons [duplicate]

The work done by tension and normal forces are conservative or non-conservative? Tension as well as normal forces does work but has no field. Simultaneously their work is not always path dependent. ...
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### General treatment of surface tension non-relativistic classical theory

I'm reading lecture notes on fluid mechanics course, and I wrote that an algebraic definition of surface tension can be constructed from work per unit area to balance the forces along the surface. ...
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### Mechanics | Use the work-energy principle to find the speed of the book as it hits the floor [closed]

Problem A small book of mass $m$ is held on a rough straight desk lid which is inclined at an angle $\alpha$ to the horizontal, where $\tan\alpha=\frac34$. The book is released from rest at a distance ...
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### Question regarding kinetic energy of a body

Suppose you pushed a block very hard for a small interval of time. Then it traveled some distance 'S' and stops due to friction. You haven't applied force upto the 'S' distance. The force applied by ...
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### Question regarding kinetic energy and final velocity of the body

Suppose there is block of mass 'M' kg . You applied the force of 'F'N on it , as a result it get accelerated. Then it acquired final velocity 'v'. The kinetic energy of the block is 1/2(MV²). My ...
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### Velocity- and time-dependent forces can not be conservative [duplicate]

I have already seen many posts about this specific question but in only a few of those mathematically rigorous answers were given. Unfortunately none of them are accessible at my level (first year ...
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### In an isothermal process there is no change in internal energy, but why in an isobaric one?

In an isothermal process, the heat Q added (which increases the temperature and internal energy) is exactly cancelled out by the work W done by the gas in the environment (which lowers the temperature ...
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### Work done by battery [closed]

In charging a capacitor to a charge $Q$ Is there an equivalent to this in setting up current through an inductive circuit? Energy stored in inductor $= 1/2Li^2$ What would be the work done in setting ...
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### Why is the friction in the motor wrong as an answer to wasted energy in this question?

I do not understand why the answer to part b)ii) cannot be energy lost to friction within the motor as the work done by the motor should be the total work done to move the cyclist and should include a ...
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### Enthalpy, why is work only partially done?

If a system with const. pressure can change it's volume free, a heat transfer into the System results in a partial work done, which gives back the inner energy addet partial back to the environment. (...
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### A ball of mass 22g moves to the left at a speed of 35 m / s [closed]

A ball of mass 22g moves to the left at a speed of 35 m / s. How much work needs to be done on the ball to start moving to the right at a speed of 35 m / s. When considering ignore any energy losses
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### What is the source of isothermal work?

The usual explanation of isothermal work, especially in the context of the Carnot cycle, is that the "heat" absorbed in the isothermal leg is converted into "work" done on the ...
1 vote
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### Conservation of energy and work done by a torque [duplicate]

Suppose you let a solid roll down an incline without slipping, from height $h$. My textbook gives the following conservation of energy relation $$mgh = \frac{1}{2}mv_{cm}^2 + \frac{1}{2}I\omega^2.$$ ...
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### Change in gravitational potential energy when the work is zero

I may be misunderstanding the whole concept , but my doubt is this. Let us say there is an isolated system comprising of a rock and the Earth. If I was to lift the rock up with a force equal to the ...
1 vote
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### What is the meaning of external work in electric potential?

We learned that $$-Work = \Delta U = q(Va-Vb).$$ However, we write that $$W = q(Va-Vb)$$ in this question. Why don't we write the minus sign in the equation? How does external work affect the minus ...
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### Different result when deriving electric force as $dW/dr$ and $-dU/dr$

Work done by electric field, $W$ is the negative of the change in electric potential energy, $U_r$. $$W=-\Delta U$$ By considering an infinitesimal change in EPE, we can deduce that electric force, \$...
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### What is the difference between kinetic friction and internal kinetic friction?

I came across the following question in my homework assignment: Which of the following statements is TRUE for a system comprising of two bodies in contact exerting frictional force on each other : (A) ...