Projectile Find x Given y

##This is how to execute the find x given y code I gave you without the wonders of VPython
import math

###set givens for this problem
##Global givens
V = 5
theta = 20
ballm = 0.1 # mass in kg
deltat = 0.01
t = 0
#Air Drag factors
Cd = 0.5
A = 0.01
p = 1.2

##x, y specific givens
y0 = 0
y = 2
x0 = 0

#Convert angle to radians, calc components of vectors
#and vectorize everything that ought to be vectorized
#This is where it gets messy...
theta = theta*math.pi/180 #converts angle to radians
vy0 = V*math.sin(theta)
vx = V*math.cos(theta)
#What follows are called 'lists'.  They are not
#vectors, but we'll pretend they are because it's
#the best option we have.
ballv = [vx, vy0, 0]
ballpos = [x0, y0, 0]
g = [0,-9.8,0]
#Initialize zero vectors of length 3 (for x, y and z directions)
Fg = [0,0,0]
Fd = [0,0,0]
Fnet = [0,0,0]
balla = [0,0,0]

#Is the ball ending up above, below or at the same height as it starts?
finalH = 1
if(y > y0):
    finalH = 2

#Python is an index-0 language, which means the first item in a list is labeled as the 0th item
#The next item is the first, etc.  To access a particular item from a list, you can
#simply type in the list name (like ballpos) and then right next to it, in square brackets,
#type in the index number for that item.  Item 1 (the second item) in ballpos corresponds
#to the y-position of the ball.
while((ballpos[1] < y and finalH > 1) or (ballpos[1] >= y and finalH == 1)):
    
	#This is a 'for loop'.  A for loop basically says, 'For every item from this here
    #first number (0 in the below example) to this other number (the length of the ballpos list)
    #execute the following code.
    #In this case, i goes from 0 to 2, and what it allows us to do is perform the same
    #set of calculations for every item in our various lists.  Since each direction is
    #independent, we can do all the x-axis stuff first, then the y-axis, then the z-axis
    for i in range(0, len(ballpos)):
        Fg[i] = ballm*g[i]
        Fd[i] = -0.5*Cd*p*A*ballv[i]*ballv[i]
        Fnet[i] = Fg[i] + Fd[i]
        balla[i] = Fnet[i]/ballm
        ballv[i] = ballv[i] + balla[i]*deltat
        ballpos[i] = ballpos[i] + ballv[i]*deltat

#Evaluate whether we've hit the desired height -- may be hit twice!
    if(ballpos[1] > y and finalH > 1):
        finalH = 1
        print(t, ballpos[0], ballpos[1], y)
    if(ballpos[1] < y and finalH > 1 and ballv[1] < 0):
        print("Not going to make it!")
        break

t += deltat

print(t, ballpos[0], ballpos[1], y)

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