All Questions
33
questions
0
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3
answers
80
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Question regarding gravitational force as external force
So, I was watching a lecture on YouTube for problems on conservation of energy and momentum and I don't quite understand this:
In this question, mass $M$ is released from the peak of the smooth ...
0
votes
1
answer
23
views
Finding the spring constant and magnitude of acceleration when it is dropped with the top attached to a ceiling [closed]
I've tried finding the potential energy by using PE = mgh then using PE = 1/2kx^2 to find k and setting PE = KE to find PE using velocity but neither is correct when finding the spring constant. I don'...
- 3
5
votes
1
answer
114
views
Insecurity about introductory classical mechanics [closed]
This is a problem I encountered, but not a homework assignment, I'm not only just looking for solutions here... This is my first time encountering questions like this, I'm sure you remember the first ...
- 287
0
votes
1
answer
97
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Lorentz force from potential- extra term?
I'm trying to verify the E.M potential energy $U= \int{A_\mu J^\mu} = q(\phi - A_j v^j )$ by using the connection:
$$
F= - \frac{\partial U}{\partial r} + \frac{d}{dt} \frac{\partial U}{\partial v}
$$...
- 2,141
1
vote
1
answer
34
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Bar released from upright position rotates about a lower hinge before being caught by a steel cable, how to calculate the tension on the cable? [closed]
I wish to check the safety factor of a steel cable that I've designed to catch a heavy bar that rotates freely due to the gravitational force acting on it.
From the upright position, I'm assuming that ...
- 11
0
votes
1
answer
178
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Goldstein equation 1.33
I am trying to read from Goldstein for self-study but I am stuck on equation 1.33. Let me restate some of the lines from Goldstein (with some modification):
If $\textbf{F}_{ij}$ (internal force, ...
- 101
0
votes
1
answer
96
views
How do I integrate this function? [closed]
I have an exercise where I have to calculate the potential energy function $U(x)$ of this force $F$. I know the function is given by integrating $-F$, but how do I do this? $c$ is a constant, and a ...
6
votes
2
answers
2k
views
Bertrand's theorem and nearly-circular motion in a Yukawa potential
The question has arisen as a result of working on part b of problem 3.19 in Goldstein's Classical Mechanics book.
A particle moves in a force field described by the Yukawa potential $$ V(r) = -\frac{...
- 1,031
1
vote
1
answer
2k
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Force derived from Yukawa potential
This is with regards to problem 3.19 from Goldstein's Classical Mechanics,
A particle moves in a force field described by the Yukowa potential $$ V(r) = -\frac{k}{r} e^{-\frac{r}{a}},
$$ where $k$ ...
- 1,031
0
votes
1
answer
60
views
What is the potential energy of the spring? [duplicate]
What is the potential energy of the spring?
On the left side there is a gravitational force $mg$ acts on the spring, same on for the right side. So, If force $mg$ streches the spring $x$ units then $...
- 699
1
vote
1
answer
383
views
Weight and potential energy for a spring pendulum
Consider a spring pendulum like in this figure
suppose the spring is arranged to lie in a straight line and its equilibrium lenght is $l$.
Consider the unit vectors $e_1, e_2$, $e_x, e_{\theta}$ like ...
- 145
4
votes
2
answers
3k
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Proof of total energy is constant in a central force field
I saw many proofs of total energy is constant in a central force field. But all the proofs end up showing this formula $$m[{\dot r}^2 + r ^2{\dot \theta}^2 ]+ \int f(r)dr = E$$ is constant. But ...
- 1,149
0
votes
2
answers
75
views
Potential energy function
I've been given
"A particle of mass m moves under a force $F = −cx^5$, where $c$ is a positive constant. Determine the potential energy function."
I've obtained:
Is this correct? I've separted ...
0
votes
2
answers
42k
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How to get height from potential energy? [closed]
I am making a spring launcher for an RC car. but i am trying to understand elastic potential energy of a spring and hooks law. this is what i have.
The car will weigh 200 grams.
The spring has a ...
- 21
0
votes
2
answers
2k
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Getting 2 different answers when finding spring constant $k$ when gravity is involved
OK, so I've been wracking my brain for the past hour trying to figure out how to calculate k in a problem like this:
A mass of 10 kg is attached to a spring hanging from the ceiling. It is released,...
