## Gravity and Classes

from visual import *
scene.height=700
scene.width=800
lab1 = label(pos=(-5,-5,0))
s=" "
prose = label(pos=(-5,-4,0))
while ord(s[0])!=10:
if scene.kb.keys:
s = scene.kb.getkey()
print ord(s[0])
prose.text += s
initvel=float(prose.text)
earth.velocity = vector(0,0,0)
moon.velocity = vector(initvel,0,0)
mmass=7.4e22
emass=6e24
earthtomoonratio = 384400000/mag(earth.pos-moon.pos)
earthtomoondist = earthtomoonratio*mag(earth.pos-moon.pos)
print earthtomoondist
scene.autoscale=0
d=.25
while 1:
rate(800)
etomvec = vector(moon.pos-earth.pos)
mtoevec = vector(earth.pos-moon.pos)
etomnorm = norm(etomvec)
mtoenorm = norm(mtoevec)
gforce = (6.7e-11 * emass * mmass)/ earthtomoondist**2
print gforce
evec = gforce*etomnorm/emass
mvec = gforce*mtoenorm/mmass
earth.velocity=earth.velocity + evec * d
print "earth velocity is",earth.velocity
lab1.text = str(mag(earth.velocity))
moon.velocity=moon.velocity + mvec * d
earth.pos = earth.pos+earth.velocity*d
moon.pos = moon.pos+moon.velocity*d
earthtomoondist = earthtomoonratio*mag(earth.pos-moon.pos)

from visual import *

class Planets:
def __init__(self,v,name,mass,xpos,ypos):
self.view = v
self.name = name
self.mass = mass

def getName(self):
return self.name

plist = []
for x in range(3):

name=raw_input("enter name")
mass=input("enter mass")
xposition = input("enter x position")
yposition = input("enter y position")
view = sphere(pos=(xposition,yposition,0),color=color.blue)
temp = Planets(view,name,mass,xposition,yposition)
temp.view
plist.append(temp)

print plist[1].getName()
print plist[0].mass
newxpos = input("enter new xpos for first planet")
plist[0].view.pos.x=newxpos

from visual import *

scene.autoscale=0
scene.height=700
scene.width=800

class Planets:
def __init__(self,v,name,mass,xpos,ypos,vel):
self.view = v
self.name = name
self.mass = mass
#set the velocity

def getPosition(self):
#return position of the object

#make get name method
return self.name

def findVelocity(self,plist,gratio,d,n):
tvec = vector(0,0,0)
for x in range(n):
if self.name!=plist[x].getName():
nv=norm(plist[x].getPosition()-self.view.pos)
#find the distance between the 2 planets
#find the gravity between the 2 planets
tvec = tvec + (gforce*nv)/self.mass
self.velocity=self.velocity + tvec * d

def updatePosition(self,d):
print d
#find the new position using the new velocity and time increment

names = ["earth","moon1","moon2","moon3"]
masses = [6e+24,7.4e+22,7.4e+22,7.4e+22]
colors=[color.blue,color.red,color.yellow,color.magenta]
xpos = [0,0,-6,0]
ypos = [0,6,0,-6]
ivelocities = 0,0,0],[.1,0,0],[0,.1,0],[-.1,0,0
earthtomoonratio = 384400000/6   #dist to moon div by dist on screen
#make the empty list
numPlanets=4
for x in range(numPlanets):

name=names[x]
#get the mass
xposition = xpos[x]
#get y position
#get velicity