VPython.ipynb

Kernel: Python 2 (SageMath)

from __future__ import division, print_function
from vpython import *
from math import *

## SETTING UP THE SCENE ##
scene = canvas()

scene.waitfor

gray = (0.7,0.7,0.7)
floor = box(pos=vector(0,-1.5,0),length=2, height=0.1, width=2)

ball = sphere(pos=vector(0.55,0.25,0), radius = 0.075, color=color.green)
ball.velocity = vector(0,0,0)

torso = cylinder(pos=vector(-0.5,-0.5,0), axis=vector(0,1,0), radius=0.2, color=color.red)
lleg = cylinder(pos=vector(-0.6,-1.5,0), axis=vector(0,1,0), radius=0.1, color=color.blue)
rleg = cylinder(pos=vector(-0.4,-1.5,0), axis=vector(0,1,0), radius=0.1, color=color.blue)
arm = cylinder(pos=vector(-0.5,0.25,0), axis=vector(1,0,0), radius=0.1, color=color.red)

scene.autoscale = 0

## THE PHYSICAL DYNAMICS ##

dt = 0.001
while 1:
    rate(200)
    ball.pos = ball.pos + ball.velocity*dt
    ball.velocity.y = ball.velocity.y - 9.8*dt
    if (ball.pos.y < -1.5):
        ball.velocity.y = -ball.velocity.y

<IPython.core.display.Javascript object>

scene=canvas(title="Electric field due to uniformly charged ring")
scene.background=color.white

R=0.02 #radius of ring in m
Q=1e-9 #charge of ring in C
N=4 #number of unique pieces

#draw the objects
myring=ring(pos=vector(0,0,0), radius=R, axis=vector(0,0,1), color=color.blue, thickness=0.02*R)
zaxis=cylinder(pos=-2*R*myring.axis, radius=0.015*R, axis=4*R*myring.axis, color=color.black)
point=sphere(pos=R*myring.axis, color=color.red, radius=5*zaxis.radius)

oofpez=9e9 #1/(4pi epsilon_0) in N m^2/C^2
dq=Q/N #charge of a piece
dtheta=2*pi/N #theta increment for our loop
theta=dtheta/2 #initial theta for first piece of loop
Enet=vector(0,0,0) #net electric field of all pieces

rpoint=point.pos #location of the point in space to calculate E field

scale=1.2*mag(rpoint)/8000 #used to scale the arrows representing E-field

while theta<2*pi:
    rpiece=R*vector(cos(theta),sin(theta),0) #location of piece
    r=rpoint-rpiece #vector from piece to point in space
    rmag=mag(r) #magnitude of r
    rhat=norm(r) #unit vector for r
    dE=oofpez*dq/rmag/rmag*rhat #Electric field due to piece at rpoint
    Enet=Enet+dE #net electric field of the first one up to this one
    particle=sphere(pos=rpiece, radius=point.radius, color=color.yellow) #draw a particle at center of piece
    dEvector=arrow(pos=rpoint, axis=scale*dE, color=color.magenta, shaftwidth=point.radius/2)
    theta=theta+dtheta

print("The net electric field = ",Enet, "N/C")
Evector=arrow(pos=rpoint, axis=scale*Enet, color=color.orange, shaftwidth=point.radius/2)

<IPython.core.display.Javascript object>

The net electric field =  <-0.000000, -0.000000, 7954.951288> N/C

from vpython import *

scene = canvas()
print("""
Right button drag to rotate "camera" to view scene.
  On a one-button mouse, right is Command + mouse.
Middle button to drag up or down to zoom in or out.
  On a two-button mouse, middle is left + right.
  On a one-button mouse, middle is Option + mouse.
""")

side = 4.0
thk = 0.3
s2 = 2*side - thk
s3 = 2*side + thk
wallR = box (pos=vector( side, 0, 0), size=vector(thk, s2, s3),  color = color.red)
wallL = box (pos=vector(-side, 0, 0), size=vector(thk, s2, s3),  color = color.red)
wallB = box (pos=vector(0, -side, 0), size=vector(s3, thk, s3),  color = color.blue)
wallT = box (pos=vector(0,  side, 0), size=vector(s3, thk, s3),  color = color.blue)
wallBK = box(pos=vector(0, 0, -side), size=vector(s2, s2, thk), color = vector(0.7,0.7,0.7))

#ball = sphere (color = color.green, radius = 0.4)
ball = sphere (color = color.green, radius = 0.4, make_trail=True, interval=5, retain=30)
#ball = cone (color = color.green, radius = 0.4, make_trail=True, interval=5, retain=30)
ball.mass = 1.0
ball.p = vector (-0.15, -0.23, +0.27)

side = side - thk*0.5 - ball.radius

display(scene)

dt = 0.5
t=0.0
while t < 2000:
  rate(100)
  t = t + dt
  ball.pos = ball.pos + (ball.p/ball.mass)*dt
  if not (side > ball.pos.x > -side):
    ball.p.x = -ball.p.x
  if not (side > ball.pos.y > -side):
    ball.p.y = -ball.p.y
  if not (side > ball.pos.z > -side):
    ball.p.z = -ball.p.z

<IPython.core.display.Javascript object>

import ipywidgets as wd
from vpython import *

# For some reason, this program that uses widgets sometimes doesn't make the 3D display without a restart

# This is an experiment in using Jupyter widgets (button, slider, menu).
# Compare with the similar program in the Example programs at glowscript.org.
# Ideally, we would like to use the same widget statements in both GlowScript and Jupyter VPython.

scene.width = 350
scene.height = 300
scene.range = 1.5
scene.title = "Buttons, Sliders, and Drop-down Menus"

box_object = box(visible=True)
cone_object = cone(visible=False, radius=0.5)
pyramid_object = pyramid(visible=False)
cylinder_object = cylinder(visible=False, radius=0.5)
objects = {'box':box_object, 'cone':cone_object, 'pyramid':pyramid_object, 'cylinder':cylinder_object}

currentobject = box_object
currentobject.color = color.cyan

b = wd.Button(description='Pause')
c = wd.Button(description='Red')
m = wd.Dropdown(options=['box', 'cone', 'cylinder', 'pyramid'], value='box',
                           description='Object:')
container = wd.HBox(children=[b,c,m])
display(container)
sl = wd.FloatSlider(description='Rotation speed:', min=20, max=500, step=1, value=250)
display(sl)

running = True

def b_handler(s):
    global running
    running = not running
    if s.description == 'Run': s.description = 'Pause'
    else: s.description = 'Run'
b.on_click(b_handler)

def c_handler(s):
    if s.description == 'Red':
        s.description = 'Cyan'
        currentobject.color = color.red
    else:
        s.description = 'Red'
        currentobject.color = color.cyan
c.on_click(c_handler)

def m_handler(s):
    global currentobject
    col = currentobject.color
    currentobject.visible = False
    currentobject = objects[s['new']]
    currentobject.color = col
    currentobject.visible = True
m.observe(m_handler, names='value')

while True:
    rate(100)
    if running:
        currentobject.rotate(angle=1e-4*sl.value, axis=vec(0,1,0))

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