particle_turtle.py

from turtle import *
import random as r

RADIUS = 50

# visual of the circle
c = Turtle()
c.penup()
c.setpos(c.pos()[0], c.pos()[1]-RADIUS)
c.pendown()
c.color('blue')
c.circle(RADIUS)

# particle
t = Turtle()
t.color('red')

# main loop
count = 0
while True:
    t.forward(5)
    if r.randint(0, 1) == 0:
        t.left(r.randint(0, 100))
    else:
        t.right(r.randint(0, 100))
    if abs(t.pos()[0]) >= RADIUS or abs(t.pos()[1]) >= RADIUS:
        break
    count += 1
done()

# print out the number of moves the particle made
print str(count)