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1 vote
1 answer
163 views

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 ...
Bapi Basak's user avatar
1 vote
2 answers
675 views

How do we find the average value of gravitational potential energy over one orbit?

We just completed orbital dynamics in my university astrophysics class. The textbook we are using is Carroll and Ostlie. In the textbook, it is mentioned that the average gravitational potential ...
Siddharth Yajaman's user avatar
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{...
Lopey Tall's user avatar
  • 1,031
1 vote
2 answers
79 views

Problem involving gravitational potential energy [closed]

Two uniform solid spheres of equal radii $R$, but mass $M$ and $4M$ have a centre separation of $6R$. The two spheres are held fixed. A projectile of mass $m$ is projected from the surface of the ...
Quantum-meatball's user avatar
3 votes
4 answers
710 views

Rocket Leaving Earth's Gravitational Field

I stumbled across this seemingly simple question that really stumped me on further thought: A rocket is intended to leave the Earth's gravitational field. The fuel in its main engine is a little ...
confused internet stranger's user avatar
1 vote
3 answers
8k views

What makes an orbit stable or unstable?

I have an assignement, where I have a given central potential $V(x)=-\frac{K}{6r^6}$ and object with an angular momentum $L$. I've calculate the radius of a circular orbit, which I've done by ...
AndrasG's user avatar
  • 69
0 votes
2 answers
3k views

How to show that the gravitational potential energy of a two particle system is -2 times the total kinetic energy, without using the virial theorem?

Consider a two-particle system with identical masses, orbiting in circles about their center of mass. I'm supposed to prove that: $$U_p = -2U_k$$ With $U_p$ potential energy of the system, and $U_k$ ...
user55789's user avatar
  • 291