Aundrea Sams
Momentum Lab
from visual import *
from visual.graph import *
scene.y = 400 # move animation window down 400 pixels from top of screen
track = box(pos=vector(0,-.05, 0), size=(1.0, 0.05, .10))
cart = box(pos=vector(-0.5,0,0), size=(0.1, 0.04, 0.06), color=color.green)
cart.m = 0.80
cart.p = cart.m*vector(0.7, .1, 0)
mgraph = gcurve(color=color.cyan)
cart.trail = curve(color=color.red)
deltat = 0.01
t = 0
while t<3.0:
cart.pos = cart.pos + (cart.p/cart.m)*deltat
t = t + deltat
rate(100)
Fnet = vector(-0.4, 0, 0)
cart.p = cart.p + Fnet*deltat
mgraph.plot( pos=(t, cart.p.x) )
#print "t=", t, "cart.p=", cart.p
cart.trail.append(pos=cart.pos)
• (1) Using the printed list of momentum vectors, calculate p v Δ . That is, pick one of the vectors to be the final
momentum, and subtract from it the vector just above it, which is the initial momentum:
Δp = p f − pi =
-.508+.504 = -.004
-.004/.01 = -.4
• (2) Calculate the vector F Δt net
F Δt = <-.4,0,0>
• (3) Do your calculations show that the change in momentum p v Δ is equal to F Δt net
Yes, because -.4 = -.4
• (4) Look at the printed list of momentum vectors again. Why aren’t the y or z components of the momentum
changing?
Since there is no force in the y or z direction, there cannot be any change in momentum. F Δt =Δp
