这是我在这里发表的第一篇文章。 所以我试图使用visual python制作模型太阳系。我将每个行星定义为一个球体，具有半径，与太阳的距离，质量和动量变量。然后将每个行星（或身体）放入列表结构中。正如你所看到的，我有一个[地球，月球，火星]列表，太阳被排除在外，我将在稍后解释。
所以当我试图计算每个身体对彼此身体造成的力时，我的问题就来了。我在这里做的是，对于身体列表中的每个第i个值，计算该物体与第n个物体之间的力，列表体中第i个物体上的力是第i个物体和每个物体之间的力的总和。正文从0到列表末尾。 （即列表中每个其他机构所有部队的总和）
这适用于月球和火星（列表中的第2和第3项），但不适用于地球。下面代码的输出是，
<3.57799e+022, 0, 0>
<4.3606e+020, 0, 0>
<1.64681e+021, 0, 0>
<-1.#IND, -1.#IND, -1.#IND> - this is the total force on earth.
<0, 2.07621e+027, 0>
<0, 9.83372e+027, 0>
from visual import *
AU = 149.6e9
MU = 384.4e6 # moon - earth orbital - radius
MarU = 227.92e9
G =6.673e-11
sun_mass =2e30
sun_radius =6.96e8
earth_mass =6e24
earth_radius =6.37e6
moon_mass =7.35e22
moon_radius =1.74e6
mars_mass = 6.41e23
mars_radius = 3390000
sun = sphere ( pos =(0 , 0 ,0) , velocity = vector (0 ,0 ,0) ,mass = sun_mass , radius =0.1* AU , color = color . yellow )
earth = sphere ( pos =( AU , 0 ,0) ,mass = earth_mass , radius =63170000, color = color . cyan ,make_trail=True )# create a list of gravitating objects
moon = sphere ( pos =( AU+MU , 0 ,0) ,mass = moon_mass , radius =17380000 , color = color . white, make_trail=True )
mars = sphere ( pos =( MarU , 0 ,0) ,mass = mars_mass , radius = mars_radius , color = color . red, make_trail=True )
#initialise values:
we = 1.9578877e-7
wm = sqrt(G*earth.mass/3.38e8**3)
wma = 9.617e-5
dt = 3*60
earth.mom = vector(0,1.5e11*earth.mass*we,0)
mars.mom = vector(0, 9.833720638948e+27,0)
moon.mom = moon.mass*(earth.mom/earth.mass+vector(0,-3.48e8*wm,0))
bodies = [earth, moon, mars]
*N = 0
initialdiff = 0
for i in bodies:
initialdiff = i.pos - sun.pos
TotalForce = (G * i. mass * sun. mass * norm ( initialdiff )/ initialdiff . mag2)
print TotalForce
while N < len(bodies):
if N!=i:
diff = i.pos - bodies[N].pos
Force = (G * i. mass * bodies[N]. mass * norm ( diff )/ diff . mag2)
TotalForce = TotalForce + Force
i.mom = i.mom+TotalForce*dt
N = N+1
else:
N = N+1
print earth.mom
print moon.mom
print mars.mom*
感谢您提供任何帮助。
答案 0 :(得分：0)
'''Abel Tilahun HW 3 '''
# 02/03 / 2015
# make the necessary imports , visual import gives visual output, cos, sin and pi allows calculation of the positions
# in real time. The numpy arange import returns evenly spaced values within a given interval (angles)
from visual import *
from math import cos,sin,pi
from numpy import arange
# i used 'a' to magnify the sizes of the planet for better visualization
a=600
# the following line defines a sphere for the sun centered at the origin(0,0,0) all the other planets are positioned at a radial distance from this center.
Sun=sphere(pos=(0,0,0),radius=6955500*(a/100),color=color.yellow)
#the next 5 commands code the planets with their center being positioned at a distance of the radii of their orbit. Their radii are multiplied by a factor of 'a' to magnify them
Mercury=sphere(pos=vector(579e5,0,0),radius=2440*(a),color=color.red)
Venus=sphere(pos=vector(1082e5,0,0),radius=6052*a,color=color.orange)
Earth=sphere(pos=vector(1496e5,0,0),radius=6371*a,color=color.green)
Mars=sphere(pos=vector(2279e5,0,0),radius=3386*a,color=color.white)
Jupiter=sphere(pos=vector(7785e5,0,0),radius=69173*(a),color=color.cyan)
Saturn=sphere(pos=[14334e5,0,0],radius=57316*(a),color=color.magenta)
# the for loop calculates position of the planets by changing
# the arange function increases the angle from 0 to pi with a small increment of 0.025 each time
for theta in arange(0,100*pi,0.025):
rate(30)
x = 579e5*cos(theta)
y = 579e5*sin(theta)
Mercury.pos = [x,y,0]
x = 1082e5*cos(theta)
y = 1082e5*sin(theta)
Venus.pos = [x,y,0]
x = 1496e5*cos(theta)
y = 1496e5*sin(theta)
Earth.pos = [x,y,0]
x = 2279e5*cos(theta)
y = 2279e5*sin(theta)
Mars.pos = [x,y,0]
x = 7785e5*cos(theta)
y = 7785e5*sin(theta)
Jupiter.pos = [x,y,0]
x = 14334e5*cos(theta)
y = 14334e5*sin(theta)
Saturn.pos = [x,y,0]