All Questions
Tagged with newtonian-gravity energy
125
questions
0
votes
2
answers
237
views
Total energy of a satellite
I have learnt that change in potential energy in any conservative force field is equal to the negative of work done by that field through a distance. While applying the same for gravitational ...
- 727
0
votes
2
answers
88
views
How to derive the equation $-G\frac{Mm}{r_1}+G\frac{Mm}{r_2}=\frac{1}{2}mv_1^2-\frac{1}{2}mv^2_2$?
I was just wondering how the following equation is derived:$$-G\frac{Mm}{r_1}+G\frac{Mm}{r_2}=\frac{1}{2}mv_1^2-\frac{1}{2}mv^2_2~?$$
I already understand why the work $W$ done in moving an object ...
- 379
0
votes
2
answers
55
views
Energy to counteract gravity without doing work? [duplicate]
Say I wanted to keep a body of 10kg at a certain altitude above the ground. If I elevate it 1m with my own arms or by any other means (with a drone, pulley system...) I'm spending energy in the form ...
- 115
1
vote
1
answer
2k
views
How much vertical weight/height do I need to store 33 kWh of energy? [closed]
My question is the feasibility of a vertical mechanical weight battery, but unlike previous questions, I wanted to give a precise scenario and see if my math is right (which I doubt)
First, it takes 1....
- 21
0
votes
4
answers
510
views
How work done by a force on a body is negative?
The work done is the product of force acting on a body and the displacement of the body in the direction of the force.
The gravitational potential $\text{energy}=Mgh$ is the negative of the work done ...
0
votes
2
answers
420
views
How much more net energy do I use walking up hill?
I have a question regarding work done / energy done.
Say a $70\mathrm{kg}$ man walked $100\mathrm{m}$ on a horizontal surface as a constant speed, is it correct to assume the energy done by this man ...
-1
votes
2
answers
46
views
The effect of potential energy in the absence of conservative force [closed]
Imagine a hypothetical situation, where we throw a ball from the earth's surface and after certain time $t$ the ball's final velocity is equals to 0. And a that instance, gravity doesn't exist (...
- 483
0
votes
2
answers
2k
views
Work done moving a satellite into higher orbit
I am confused about the concept of work in relation to conservative and non-conservative forces.
When transferring a satellite from a lower orbit into a higher orbit via a Hohmann transfer, my ...
- 97
1
vote
6
answers
502
views
In the limit, does walking slowly downstairs cost me as much energy as walking upstairs?
I am not a physicist.
If I allow myself to roll down a hill, then apart from receiving bruises, I will expend no energy.
Having suffered ill-health recently, it seemed reasonable for me to restart my ...
- 3,006
1
vote
1
answer
93
views
Some questions regarding graviational potential energy and the concept of potential energy in general
Starting off, I first want to know the relation between work and potential energy.
$\Delta\mathbf U = - W $
How was this expression formulated?
Moving on,
My second doubt was in the derivation of the ...
- 82
0
votes
2
answers
59
views
Does a falling body add energy to the earth?
Gravitational potential energy is inversely proportional to distance:
$$V = G\frac{ m_1 m_2 }{d}.$$ when an asteroid is extremely far from earth, its gravitational potential energy (relative to earth) ...
0
votes
3
answers
133
views
Amount of work: clarifications
If to lift an object of mass $m$ a force greater than $mg$ is required then why do we take the amount of work done in lifting an object as $mgh$ could someone please explain that to me?
- 356
4
votes
2
answers
586
views
Feynman Lectures Chapter 4.2: Understanding the weight-lifting machine visually
Why a non-reversible weight lifting machine cannot lift higher that a reversible one is related to my current post, but everyone in that thread seems to have understood how Feynman's simple machine ...
- 216
0
votes
0
answers
16
views
Kinetic energy in "interplanetary" Gravitational potential energy problem?
For a system of two completely stationary planets both of the same radius and mass, when launching a projectile (e.g. a rocket) from point A on the left planet - assuming we know U - minimal kinetic ...
- 1
0
votes
0
answers
61
views
How to calculate the total energy of a planet at rest?
Let's just say we have the Earth-Moon system isolated in space, with Earth at rest, and the moon orbiting it.
How can we calculate the total energy of Earth in such a case (Kinetic energy would be ...
