Escape Speed and Atmospheric Temperatures of Planets: Calculations and Analysis

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SUMMARY

The escape speed for a particle to leave a planet's gravitational influence is calculated using the formula (2GM/R)^(1/2), where M is the planet's mass, R is its radius, and G is the gravitational constant. The root mean square (rms) speed of hydrogen molecules (H2) in Jupiter's atmosphere at 140K is approximately 1.321 x 10^3 m/s, while in Earth's atmosphere at 220K, it is about 1.656 x 10^3 m/s. The significant presence of hydrogen in Jupiter's atmosphere, comprising 89% of its molecules, is attributed to its lower escape velocity compared to Earth. Ceres, with a mass of 0.014 times that of the Moon and a surface temperature of 200K, raises questions about the existence of an oxygen atmosphere due to its low gravitational influence.

PREREQUISITES
  • Understanding of gravitational physics and escape velocity
  • Familiarity with the ideal gas law and root mean square speed calculations
  • Knowledge of planetary atmospheres and their composition
  • Basic understanding of thermodynamics and temperature effects on gas behavior
NEXT STEPS
  • Calculate escape velocities for various celestial bodies using (2GM/R)^(1/2)
  • Explore the ideal gas law and its applications in different atmospheric conditions
  • Investigate the composition and characteristics of planetary atmospheres, focusing on gas retention
  • Research the physical properties of Ceres and its potential for hosting an atmosphere
USEFUL FOR

Astronomers, astrophysicists, students studying planetary science, and anyone interested in the dynamics of planetary atmospheres and escape velocities.

zferic28
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a) Show that the escape speed for a particle to leave the gravitational infuence of a planet is given by (2GM/R)^1/2, where M is the mass of the planet, R is its radius, and G is the gravitational constant.
b) The temperature near the top of Jupiter's multicolored cloud layer is about 140K. The temperature at the top of the Earth's troposphere, at an altitude of about 20km, is about 220k. Calculate the rms speed of huydrogen molecules (h2) in each of these environments. Give your answers in the m/s and as a fraction of the escape speed from the
respective planet.
c) Hydrogen gas is a rare element in the Earth's atm. In the atmosphere of Jupiter, by contrast, 89% of all molecules are H2. Explain why, using your results from the previous part.
d) Ceres is an asteroid with mass equal to .014 times the mass of the moon, a density of 2400kg/m^3 and a surface temp of about 200K. Suppose an astronomer claims to have iscovered an oxygen (O2) atmosphere on the asteroid Ceres. You are asked by a TV news reporter to comment on this claim. What would you say, and how would you support that?

a) I don't fully understand what I have to calculate or demonstrate in this, can someone please break this down for me? Thanks!




b) I need the formula Vrms = sqrt(3RT/M)

M of H2 = 2g/mol = .002kg/mol

Vrms Jupiter = sqrt(3x8.314x140k/.002kg) = 1.321x10^3 m/s
Vrms Earth = sqrt(3x8.314x220k/.002kg)= 1.656x10^3 m/s

I don't quite understand what I have to do to get the fraction of the escape speed relative to the planet.

I suppose use the given formula (2GM/R)^1/2 to calculate each plantes escape and then divide that number by the Vrms of Jupiter and Earth?? What is g, M, and R of jupiter?? Is 9.8m/s the gravitational force at 20km high in the Earth's atmosphere?? Please help!

c) I am guessing this will have to do with the escape velocity of each planet? Maybe Jupiter likes to hang on to it's H2 and Earth let's them go?

d) Lost me again on this one? Thanks for all the help..:confused: :confused: :confused:
 
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Once you've got the rest d) is dead easy zferic. You just plug a) and b) back in.
 

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