All Questions
55
questions
1
vote
3
answers
9k
views
Why can't we define a potential energy for a non-conservative force? [closed]
We could define potential energies for non-conservative forces too and then we could conserve it with kinetic and potential energy as we know it. But no one does that. Why is this? Please explain. Any ...
- 913
2
votes
3
answers
16k
views
Why is walking up stairs harder than walking normally?
I must admit, I'm pretty new to studying physics and I know this is a simple concept but I'm having difficulty understanding it. I've tried reading the questions here but I just need a little bit of ...
- 123
0
votes
1
answer
296
views
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
views
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
0
votes
1
answer
174
views
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
3
votes
1
answer
445
views
Confusion with curl of Lorentz magnetic force
Since the magnetic force is a no work force, $dW=\vec F\cdot d\vec r=0$ for $\vec F(\vec r)=q(\vec v(\vec r) \times \vec B(\vec r))$, therefore $\oint \vec F \cdot d\vec r=0$ by Stoke's theorem. ...
- 26.8k
2
votes
3
answers
847
views
A few questions about the concept of work
From Wikipedia: The work done by a constant force of magnitude F on a point that moves a displacement d in the direction of the force is the product:
$$W = Fd.$$
If I lift some object from a ground, ...
- 153
0
votes
4
answers
6k
views
How do you tell what forces do no work?
The total mass of the children and the toboggan is 66 kg. The force the parent exerts is 58 N (18 degrees above the horizontal). What 3 forces/ components do no work on the toboggan?
I said the ...
12
votes
2
answers
7k
views
Can a force in an explicitly time dependent classical system be conservative?
If I consider equations of motion derived from the principle of least action for an explicitly time dependent Lagrangian
$$\delta S[L[q(\text{t}),q'(\text{t}),{\bf t}]]=0,$$
under what circumstances (...
- 8,523
7
votes
1
answer
2k
views
A Question about Virtual Work related to Newton's Third Law
In describing d'Alembert's principle, the lecture note I was provided with states that the total force $\mathbb F_l$ acting on a particle can be taken as,
$$\mathbb F_l=F_l+\sum_mf_{ml}+C_l,$$
where $...
- 190