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-1 votes
1 answer
19 views

Strain energy stored in a bungee cord pulled at its midpoint [closed]

A bungee cord that behaves elastically has an unstressed length $L=.76$ m and a stiffness $k=140$ N/m. The cord is attached to two pegs, distance $b=.38$ m apart, and pulled at its midpoint by a force ...
0 votes
3 answers
80 views

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 ...
-1 votes
1 answer
135 views

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 ...
0 votes
1 answer
380 views

Gravitational Potential Energy Lab Confusion

I had a lab that tested the dependence of gravitational potential energy on its position and the goal out of each exercise was to see if kinetic energy equaled potential energy. A cart was on a flat ...
1 vote
1 answer
639 views

Textbook question on calculation of potential difference between two points

My textbook has the following question What is the potential difference between two points that are 50cm and 80cm respectively from a point charge of 2uC? Unfortunately, the textbook has not taught ...
1 vote
2 answers
2k views

Deriving gravitational potential energy using vectors

Here is my attempt at derivation: First you must find a vector function for the gravitational force. By the inverse square law, the magnitude of gravitational force between two bodies of mass $m$ ...
0 votes
1 answer
37 views

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 ...
0 votes
2 answers
993 views

Electrostatic energy of "a spherical dielectric shell and a point charge at the center"

The inner radius of the dielectric shell is $a$, and the outer radius is $b$. I tried to use the formula involving the square of the electric field, and found $E$ in three regions. But when I evaluate ...
2 votes
0 answers
50 views

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 ...
0 votes
1 answer
61 views

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 votes
1 answer
58 views

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 vote
2 answers
3k views

Hanging mass from spring/ Setting potential to 0

I'm working a problem from Taylor's Classical Mechanics Book, and it's highlighted a couple issues I never quite wrapped my head around (despite getting good marks in advanced undergrad mechanics and ...
1 vote
1 answer
130 views

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 ...
0 votes
2 answers
296 views

How do I find the energy difference between two points of a gravitational gradient?

What I'm ultimately trying to figure out is how to calculate only the potential energy attributed to the differences in the force of gravity at two distances from the Earth's center of gravity.
1 vote
2 answers
2k views

What happens when a voltmeter is connected across two parallel circuits?

Edit: Link to question. I'm looking at question 4.6. I cannot understand how to make sense of this arrangement of voltmeter, let alone answer the question. Any help is very much appreciated. Are you ...

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