All Questions
31
questions
0
votes
6
answers
280
views
Does potential energy actually exist? Or is it just a useful mathematical model? [closed]
The title basically covers it. I've actually thought about this question for a while now, and I am still not sure if I have a definitive answer. Most potential energies seem to just be the work that ...
- 183
0
votes
3
answers
88
views
Consolidating two ways to calculate work
I was wondering if I could get some help closing some fundamental gaps in my intuition of work, as it relates to force and distance travelled.
Scenario
Say we pull a 1kg box along the ground. We pull ...
- 163
1
vote
1
answer
87
views
Kinetic and Potential Energy of a multi degree of freedom (MDOF) system
Consider the following MDOF system:
$M\ddot x+Kx=F$
where $M$ and $K$ are the mass and stiffness matrix respectively, and $x$ and $F$ are the displacement and force vectors.
How can one determine the ...
- 37
0
votes
5
answers
97
views
How can potential energy increase? [closed]
If work is done on a body, the energy of the body increases. If work is done by the body, energy decreases. When we take a body up to some height, some work is done by us on the body, which is stored ...
1
vote
0
answers
119
views
Are principle of virtual work and principle of minimum potential energy same? And how is it related to Calculus of variation?
I am studying Finite element method and Classical Mechanics. I have come across three important terms
Principle of virtual work (found in Classical Mechanics)
Principle of minimum potential energy (...
- 11
0
votes
1
answer
46
views
Why is the force being the differential of a potential equivalent to it being a conservative force?
I was reading Goldstein's book on mechanics and came across this theorem:
$F(r) = - \nabla V(r)$ is a necessary and sufficient condition of the force field being conservative.
So far, I have ...
- 169
0
votes
2
answers
407
views
Is energy infinite in an electric field?
Energy is defined as the capacity to do work. Work in turn is defined as force x displacement.
An electric field exerts the field in all directions infinitely (even though the strength of that force ...
- 11
-1
votes
3
answers
173
views
Why gravitational potential away from a planet increases?
textbooks----
"potential increases towards infinity and is maximum at infinity"
But that is true only when we are seeing potential w.r.t Earth
EXPLANATION---------
So , as we know that ...
- 444
0
votes
0
answers
675
views
Lagrangian intuition [duplicate]
I am new to lagrangian mechanics and it just baffles me the idea of subtracting potential energy from kinetic energy. Why don't we use kinetic energy alone and the least action path (between two ...
- 105
2
votes
2
answers
281
views
Work done on an object whilst lifting it
Imagine to lift an object with mass $m$ from height $h_1$ to height $h_2$ and neglect the friction with air. How much work have you done on the object?
My answers (big doubt in the second one!):
...
- 1,319
1
vote
2
answers
164
views
A simple doubt regarding spring potential energy
A conceptual problem. Suppose we have a spring whose stiffness constant is $k$. The spring is attached to a wall and the other end is fastened to a block. If we pull the block by an external force ...
- 882
1
vote
1
answer
812
views
Work done for conservative forces is path independent Proof
So I’m looking at the proof for work that is path independent.
There is a line were the integral
Partial derivative V dr from r1 to r2 becomes
Partial derivative V r’ dt from t1 to t2
I’m a bit ...
0
votes
1
answer
261
views
Taylor Example 4.8. Is my reasoning sound? [closed]
This problem has been giving me all sorts of fits. For one, Taylor states that because the frictional force and normal force are forces of constraint, they produce no work. I'm trying to figure out ...
0
votes
1
answer
125
views
How is work equal to $Tds$ for an element of string in a transverse wave?
Assume that an infinitesimal element of a string is horizontal, and due to a wave passing on it, it's shape changes and is inclined as shown in the figure.
Assuming constant tension $T$ it's claimed ...
- 1,260
1
vote
3
answers
389
views
Defining potential energy in Taylor's Classical Mechanics
I'm trying to understand this sentence in introducing potential energy in John Taylor's book:
If all forces on an object are conservative, then can define a quantity called potential energy, $U (\...
- 753