Source code for RCAIDE.Library.Attributes.Planets.Earth
# RCAIDE/Library/Attributes/Planets/Earth.py
#
#
# Created: Mar 2024, M. Clarke
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# Imports
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from .Planet import Planet
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# Earth Class
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[docs]
class Earth(Planet):
"""
A class representing Earth's physical properties and gravitational characteristics.
Attributes
----------
tag : str
Identifier for the planet ('Earth')
mass : float
Mass of Earth in kg (5.98e24)
mean_radius : float
Average radius of Earth in m (6.371e6)
sea_level_gravity : float
Gravitational acceleration at sea level in m/s² (9.80665)
Notes
-----
This class implements standard Earth properties used in aerospace calculations.
Values are based on internationally accepted standards for Earth's physical parameters.
"""
def __defaults__(self):
"""This sets the default values.
Assumptions:
None
Source:
None
"""
self.tag = 'Earth'
self.mass = 5.98e24 # kg
self.mean_radius = 6.371e6 # m
self.sea_level_gravity = 9.80665 # m/s^2
[docs]
def compute_gravity(self, H=0.0):
"""
Compute the gravitational acceleration at a given altitude above Earth's surface.
Parameters
----------
H : float, optional
Altitude above sea level in meters. Default is 0.0
Returns
-------
gh : float
Gravitational acceleration at the specified altitude in m/s²
Notes
-----
**Theory**
Uses the inverse square law for gravitational acceleration:
.. math::
g(h) = g_0 \\left(\\frac{R_e}{R_e + h}\\right)^2
where:
- g₀ is sea level gravity
- Rₑ is Earth's mean radius
- h is altitude above sea level
"""
# Unpack
g0 = self.sea_level_gravity
Re = self.mean_radius
# Calculate gravity
gh = g0*(Re/(Re+H))**2.0
return gh
