Question

Consider the following VPython script that was written to model the motion of a fan cart:

from visual import *

fancart = sphere(pos=vector(10,9,0), radius=0.5, color=color.red)

mcart = 0.5
vcart = vector(4,0,0)
pcart = mcart*vcart

Ffan = vector(2,0,0)

t=0
dt=0.1
tf=0.3

while t<tf:
        rate(150)
        
        pcart = pcart + Ffan*dt
        fancart.pos = fancart.pos + (pcart/mcart)*dt
        
        t = t + dt

(a) At what location is the fan cart when the script stops running? the answer should look something like: vectorRf = < x , y , z > m.

(b) What kind of motion is this script modeling? 1/D constant force (or velocity) OR 2D constant force (or velocity)?

(c) How can you tell what kind of motion is being modeled?

Answer 1

Solution:

(a) vectorRf = <11.44,9,0> m

The loop runs 3 times with values for vectorRf after each loop calculations are <10.44,9,0> m, <10.92,9,0> m and <11.44,9,0> m

(b) The script is modeling 1/D constant force (or velocity).

(c) The vcart and Ffan variables are zero in y,z coordinates, implying the force (or velocity) is in just x-direction (1/D). It can also be seen as the location of the fan cart changes only in the x-dimension, therefore, force (or velocity) is applied only in 1/D.