All Questions
70
questions
1
vote
2
answers
1k
views
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
3
answers
522
views
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
votes
3
answers
859
views
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
views
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
8
votes
4
answers
602
views
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
1
vote
1
answer
2k
views
Solve a problem of work and energy
A man pulling sled of his daughter by a massless rope, climbing a snowy hill whose slope is equal to 15 °. Considering that the mass of the sled is $4Kg$, the girl's $26Kg$ and $\mu _c = 0,25$, ...
- 113
14
votes
5
answers
49k
views
Proof of conservation of energy?
How is it proved to be always true? It's a fundamental principle in Physics based on all of our currents observations of multiple systems in the universe. Is it always true to all systems? Because we ...
- 677
18
votes
2
answers
107k
views
Conceptually, what is negative work?
I'm having some trouble understanding the concept of negative work. For example, my book says that if I lower a box to the ground, the box does positive work on my hands and my hands do negative work ...
- 181
52
votes
4
answers
12k
views
What's the real fundamental definition of energy?
Some physical quantities like position, velocity, momentum and force, have precise definition even on basic textbooks, however energy is a little confusing for me. My point here is: using our ...
- 36.4k
1
vote
1
answer
2k
views
Energy used to stop / slow an object
I'm trying to workout how much energy (if any), I use (imagining me as an efficient machine rather than a complex bio-mechanical human) when I lower or catch a weight. I understand that when I push it ...
- 13