Comet Orbit Around the Sun: Calculating Speed

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SUMMARY

The discussion focuses on calculating the speed of a comet in an elliptical orbit around the Sun, specifically at a distance of 6 x 1012 m, which approximates Pluto's distance. The closest approach to the Sun occurs at 4.5 x 1010 m with a speed of 8.9 x 104 m/s. The conservation of mechanical energy, which includes both kinetic energy and gravitational potential energy, is the key principle used to solve for the comet's speed at the specified distance. The mass of the comet is not required for the calculations, as it can be treated as a variable in the equations.

PREREQUISITES
  • Understanding of elliptical orbits in celestial mechanics
  • Knowledge of gravitational potential energy (GPE) calculations
  • Familiarity with kinetic energy concepts
  • Basic principles of conservation of mechanical energy
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  • Study the principles of elliptical orbits and Kepler's laws
  • Learn how to calculate gravitational potential energy in the context of celestial bodies
  • Explore the conservation of mechanical energy in orbital mechanics
  • Investigate the relationship between distance from the Sun and orbital speed using the vis-viva equation
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Astronomy students, physics enthusiasts, and anyone interested in understanding the dynamics of cometary orbits and energy conservation in celestial mechanics.

jamagner
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A comet is in an elliptical orbit around the Sun. Its closest approach to the Sun is a distance of 4.5 1010 m (inside the orbit of Mercury), at which point its speed is 8.9 104 m/s. Its farthest distance from the Sun is far beyond the orbit of Pluto. What is its speed when it is 6 1012 m from the Sun? (This is the approximate distance of Pluto from the Sun.)

i have no clue how to find the speed given only the distances and the other speed
 
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Hint: What's conserved?
 
see that's what i don't know...my guess would be kinetic energy is conserved but i don't really know...i suck at physics i never know what's going on
 
Mechanical energy (kinetic energy + gravitational potential energy) is conserved.
 
so how do i use this in an equation can i set it up as a proportion
 
Initial total energy = final total energy. You'll need to know how to calculate gravitational PE.
 
What if you don't know the mass of the comet, because don't you need this to use the gravitational PE?
 
sriceb01 said:
What if you don't know the mass of the comet, because don't you need this to use the gravitational PE?
You don't need the actual mass. Just call it "m" and see what happens.
 

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