All Questions
Tagged with potential-energy homework-and-exercises
394
questions
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What are the points to note in a spring+block system? [closed]
This is the solution to a question related to spring+block system, and I have some doubts regarding the concept behind this question
The solution reads
The velocity of the block increases till the ...
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2
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50
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Energy of a spherical shell
System: spherical shell with surface density.
Objective: calculate potential energy.
I found energy through potential.
Next, I found the formula for energy through the field, which gives two ...
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1
answer
59
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Deriving expression for gravitational potential energy around a mass, $M$, using vectors
(I think my question will be somewhat related to this one: Deriving gravitational potential energy using vectors .)
I know the change in the potential energy associated with a conservative force, $\...
0
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1
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56
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Question about Problem $12$ in Chapter $11$ from Kibble & Berkshire's book
I write again the problem for convinience:
A rigid rod of length $2a$ is suspended by two light, inextensible strings of length $l$ joining its ends to supports also a distance $2a$ apart and level ...
1
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1
answer
130
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Why can we ignore the work done by gravity?
I am working through the problem above, starting with part (d). By the conservation of energy setting the spring in equilibrium as $y_0$ as the difference in length of the unstretched spring to the ...
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27
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About reference of potential energy
I have an exercise with a pendulum starting at horizontal position, then we give it a velocity of 5m/s pointing down, $z=0$ at this horizontal position and potential energy = 0. This confuses me ...
5
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3
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If a car is *accelerating* uphill, does it *gain* kinetic energy?
I had an exam yesterday on physics (9th Grade), there was a question that confused me a lot. It said: "If a Gas Car is accelerating uphill, what happens to its G.P.E and K.E?"
A: It loses ...
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Finding the Equation of motion for a vertical rotating disc with an added mass
I have been trying to figure out the equation of motion of a rotating disc with an added mass fixed on the surface of the disc at a certain distance $r$ from the disc's centre point.
I have ...
1
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1
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163
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Why is there a *minimum* energy for a particle to be captured in a $r^{-3}$ potential?
I was stuck in a central force problem from David Morin's Book "Introduction to Classical Mechanics".
The problem states that suppose there is a particle of mass $m$ moving under the ...
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2
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217
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Lagrangian function of a mass-spring-system with deflections in 2D [closed]
I’m looking for the lagrangian function of the following problem (as seen in the picture). We have a mass connected to two springs. We can deglect the mass in two dimensions.
My main problems are:
...
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45
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Question about condition for oscillation of a physical system in Lagrangian mechanics
I can't answer the following question about a (simple) physical system I have studied using Lagrangian mechanic techniques.
So, we have a straight rigid rod in a horizontal plane, symmetrically fixed ...
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93
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Potential energy involving both elastic and gravity
A block of mass $m$ is placed against an ideal spring as shown. Initially the spring (of force constant $k$) is compressed by a distance $s$. The block is then released and slides a distance d up the $...
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2
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67
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Minimum initial velocity to avoid collision [closed]
I'm having problem with the solution of this question:
Two material points with mass $m$ move along a horizontal axis subjected only to Newton's gravitational force law. At the instant $t_0=0$, one ...
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1
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98
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Triple integral gravitational potential between point and sphere [closed]
Problem for self-study: Gravitational potential between a point $\mathbf a$ and a uniform sphere, leaving out gravitational and density constants
$$
V(\mathbf{a})=\int\int\int\dfrac{1}{\vert\mathbf a -...
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3
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I know that electric potential energy is defined for a system of charges, not for a single charge. But what about electric potential?
My professor explained me in the best manner possible about the electric potential energy and why it is NOT defined for a single charge, BUT my question is as Electric potential is just electric ...
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3
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250
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Why is my answer for height negative?
Question is simple. A ball is thrown upwards with initial velocity $v_0$. How high does it go up?
Assume down is negative and up is positive and no air resistance.
KE at bottom = PE at the top:
$\...
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102
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Change in potential and kinetic energy after a photon is absorbed by a electron
This is a question from the AP Physics 2 2022 FRQ. Why does the potential energy of the atom and the kinetic energy of the electron decrease after a photon is absorbed? Shouldn't both of them increase?...
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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'...
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85
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Schrödinger-Propagator for combined linear and harmonic potential
Given the Hamiltonian
\begin{equation}
H = \frac{p^2}{2m} + V(x)
\end{equation}
The propagator for a pure harmonic potential of the form
\begin{equation}
V(x) = \frac{1}{2} m \omega^2 x^2
\end{...
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26
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Right displacement in spring potential energy [closed]
I have a doubt in general, the above problem is an example.
Here , the elastic string can be treated as a spring and we know the potential energy of a spring is $\frac{1}{2} k (x_f-x_i)^2$
So , ...
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3
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How do velocities become equal when potential energy is maximum? [closed]
I was given this diagram and asked to find the maximum potential energy during the subsequent motion if one of the blocks is projected with a kinetic energy K initially.
So I did reach upon the answer ...
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Restriction to a region of potential energy [closed]
A particle with total energy E is moving in a potential energy region U(x). Motion of the particle is restricted to the region when?
(A) U(x) > E.
(B) U(x) < E.
(C) U(x) = 0.
(D) U(x) ≤ E.
I ...
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1
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From my reference frame, why does the Earth need a huge kinetic energy [$0.5M_E(11200)^2=3.75*10^{32}$ joules] to escape me? [closed]
I wake up screaming into the void, when I see the Earth almost touching me but going away from me at 11.2 $km/s$.
I don't remember what happened before I woke up. I faintly recollect being cannoned up ...
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Gravitational potential energy of an object on Earth compared to Moon
The gravitational potential energy of a $200\,\text{kg}$ satellite $3000\,\text{km}$ above the surface of the Earth is $U=-\frac{GMm}{r}=-8.5 \times 10^9\,\text{J}$.
Would the gravitational potential ...
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434
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Finite potential well and nature of its solutions
The question I have is about nature of solutions, not a solution or a specific answer that I am looking for. If we define a potential well centred at $x=0$ as the following,
$$V(x) = \left\{ \begin{...
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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 ...
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49
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How do I visualize total potential energy of charges?
In the following exercise from University Physics with Modern Physics (Young, Hugh D.; Freedman, Roger A..)
Two point charges are at fixed positions on the $x$-axis, $q_1 = -e$ at $x = 0$ and $q_2 = ...
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2
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50
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Orientation of gravity force in energy [closed]
My apologies in advance if this is a stupid question.
A 0.20 kg rocket in a fireworks display is launched from rest and follows an erratic flight path
to reach the point P, which is 29 meters above ...
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Two charged spheres connected by a wire and one is inside the other [closed]
Two charged spheres are connected by a wire, a small sphere is located inside a bigger one. Both spheres are charged and connected through a wire. The charge of the small sphere is 20µc and the charge ...
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Position equation of $U(x)=-U_1[(\frac{x}{x_1})^3-(\frac{x}{x_1})^2 ]$
If $U(x)$ is given by $$U(x)=-U_1\left[\left(\frac{x}{x_1}\right)^3-\left(\frac{x}{x_1}\right)^2 \right]$$ can I find the position equation without harmonic aproximation?
I'm having problem with the ...
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