All Questions
Tagged with classical-mechanics work
214
questions
5
votes
2
answers
2k
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Why does the work-energy theorem need to include internal forces?
Can anyone kindly explain me why work energy theorem must also include internal forces?
The proof of work energy theorem is derived from Newton's laws of motion, but Newton's laws of motion don't ...
- 399
1
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2
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Work done by reaction forces between objects
Assume that there are no friction forces. If we had a particle sliding down a wedge that is free to move on a smooth surface, why do we ignore the work done by the reaction forces on both the particle ...
- 85
2
votes
1
answer
329
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Why does a system have to be holonomic?
So I'm doing some work from Taylor's mechanics book. He says for the problems in the book, we require the system to be holonomic - that is the number of generalized coordinates = number of Deg. of ...
- 85
2
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3
answers
522
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What was the motivation behind the work formula?
Surely there must be a reason we decided to use this as a metric for mechanical energy.How was it developed and what made it more acceptable than other work formula candidates (Like force over time, ...
- 556
3
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3
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859
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Is there an intuitive explanation of the work formula?
Upon learning calculus, I decided it was time to derive all of classical mechanics to give myself a good understanding of physics. What I found was that, while trying to do so, I would need some ...
- 556
0
votes
1
answer
404
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Classical Mechanics -- Sign of work done
It seems that work has two possible ways to decide it's sign:
Whether you take the perspective of the system or the surrounding (whether you consider work done on the system as positive, or work done ...
- 1,585
0
votes
1
answer
404
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Work and chemical energy "paradox" [duplicate]
This is a mistake I've seen many people make, a few physicists included, but I haven't ever seen a satisfactory explanation for what's going on. Apologies for the lengthy setup.
Setup
Suppose I ...
- 212
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votes
1
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Normal force, work and conservativity
I have searched very much on line, both in this site and elsewhere, but found no proof of whether the normal force is conservative or is not, in general.
Clearly, if the force is orthogonal to the ...
0
votes
1
answer
140
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Given an initial push, is work done on an object infinite in a hypothetical empty universe?
Consider a hypothetical empty universe containing a single object. Given an initial push, will the work done by the forever moving object be infinite?
- 500
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1
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Work done: kinetic energy or area under F-ds curve?
Starting from $$F=ma = m \frac{dv}{dt} = m \frac{ds}{dt} \frac{dv}{ds} = m v \frac{dv}{ds}, $$ leads to work done = integral of F.ds = integral of mvdv = change in KE.
Suppose a variable force is ...
- 71
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2
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Net work done for rubber bands
I know that work is done on a rubber band to extend it, and then the rubber band does work to contract. However, then what is the net work done?
If it returns to its original length, is the area ...
- 101
1
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2
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Understanding a graph of energy conservation with bounded and unbounded motions?
This graph is from the physics undergraduate text "Classical Mechanics by Douglas Gregory".
Above this graph was the statement:
What I didn't understand is- as stated in the under [*paragraph], won'...
- 75
0
votes
1
answer
174
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Gravitational work
As far as I know gravitational work is independent from the path of the object, and I have an object that goes up on a inclined plane to a certain height, and than, after the object reaches the edge ...
- 11
8
votes
4
answers
602
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Is there a fundamental reason not to define the work vice-versa
My question arises from something which has never been really clear: in continuum mechanics, why is strain energy defined as:
$$W=\int_\Omega \underline{\underline{\sigma}}:\mathrm{d}\underline{\...
- 734
2
votes
1
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870
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Separating the potential energy of a system of particles.
Assuming all forces derive form a conservative source and that all forces observe the strong form of the third law, how do we arrive at the following equation?
\begin{equation}
V=\sum _i V_i+\frac ...
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