#This is a shell program implementing the basic impulse-momentum analysis

#setup
from __future__ import division
from visual import *

#constants

#create objects & initial conditions
#OBJECTS:
movingblob = sphere(pos = vector(0,0,0), radius = 5, color=color.white)
	#movingblob is a sphere of radius 5 positioned at the origin


#INITIAL CONDITIONS
referencefloor = box(pos = vector(0,-.05,0), size = vector(600,.1,1),color=color.red)
        #referencefloor creates a horizontal line for use as reference for the moving blob

movingblob.mass = 15
movingblob.velocity = vector(30,40,0)
movingblob.p = movingblob.mass * movingblob.velocity
	#This assignes a starting mass, velocity, and momentum (p) to
	# the blob.  Note that this blob is moving diagonally
	# (theta = 53 degrees, magnitude = 50 units)

netforce = vector(0,-150,0)
fmag = sqrt(netforce.x**2 + netforce.y**2 + netforce.z**2)
fhat = netforce/fmag
	#netforce is the net force acting on the blob.
	# fmag is the magnitude of this force, fhat is a unit vector
	# in the direction of this net force.

t = 0
dt = 0.01
	#t is the initial time, dt is the size of the time step.

#calculations
while t<100:	#loop until 100 seconds have passed
    rate(100)   #This limits program to 100 loops per second, each of which
                # takes 0.01 s (dt), so it approximates real time
    movingblob.pos = movingblob.pos + (movingblob.p/movingblob.mass)*dt
	    #current position = prev. position + velocity * deltat
    movingblob.p = movingblob.p + netforce*dt
	    #current momentum = prev. momentum + change in momentum
	    #	(change in momentum = force * deltat)

    t = t + dt
	    #keep track of the current time