How to calculate the momentum of Pluto?

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Discussion Overview

The discussion revolves around calculating the momentum of Pluto, focusing on both classical and angular momentum. Participants explore the implications of Pluto's orbital characteristics and the conservation of momentum in celestial mechanics.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant requests assistance in calculating Pluto's momentum for a science project, indicating a lack of understanding of certain concepts.
  • Another participant states that classical momentum is calculated as mass times velocity, providing Pluto's mass and suggesting that its orbital radius and period can be used to determine velocity.
  • A follow-up question is raised regarding the ability to know Pluto's exact momentum at any point in its orbit, highlighting its eccentricity.
  • Some participants note that while momentum is conserved, the momentum of Pluto may vary throughout its orbit, suggesting a need to reference Kepler's laws.
  • There is a discussion about the distinction between linear and angular momentum, with one participant asserting that linear momentum is not conserved for Pluto due to its curved path.
  • Another participant emphasizes that conserved quantities include the linear momentum of the planet-sun system, angular momentum, and total energy, pointing out the implications of gravity as a central force.

Areas of Agreement / Disagreement

Participants express differing views on the conservation of momentum, particularly regarding linear versus angular momentum, and whether Pluto's momentum can be considered constant throughout its orbit. The discussion remains unresolved with multiple competing perspectives.

Contextual Notes

Participants reference various assumptions about orbital mechanics and the definitions of momentum, but these assumptions are not fully explored or agreed upon.

ndirishchick
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If anyone knows how to calculate the momentum of Pluto it would be great if you could let me know. I am doing a science project and do not understand parts of the project. Thanks!
 
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Classical momentum is just mass * velocity

The orbital radius is around 5.9 billion km, period is 248years so it should be easy to work out velocity.
The mass is 1.3E22kg
 
mgb_phys said:
Classical momentum is just mass * velocity

The orbital radius is around 5.9 billion km, period is 248years so it should be easy to work out velocity.
The mass is 1.3E22kg

Can we know the exact momentum of Pluto at any point in orbit? It's so eccentric.
 
pixel01 said:
Can we know the exact momentum of Pluto at any point in orbit? It's so eccentric.
But rather predictably so.
Momentum is conserved and a planet has rather a lot of momentum - as you would know if you have ever tried to stop one with your bare hands.
 
mgb_phys said:
But rather predictably so.
Momentum is conserved and a planet has rather a lot of momentum - as you would know if you have ever tried to stop one with your bare hands.

I just suspect the momentum of Pluto is not the same around the orbit, it may be quite different. I may have to look back at the Kepler's law.
 
mgb_phys said:
But rather predictably so.
Momentum is conserved and a planet has rather a lot of momentum - as you would know if you have ever tried to stop one with your bare hands.

Angular momentum is more costumary to consider here.

But for linear momentum:
mv is consreved, where v is v_radial + v_tangential.
 
The linear momentum of a planet (eg. Pluto) is not conserved. The planet follows a curved path!

Conserved quantities are linear momentum of the planet+sun system (tautologically zero in the planet+sun center of mass frame), angular momentum (gravity is a central force) and total energy (gravity is a conservative force).
 

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