# Tk_ball_velocity.py

# Tk_ball_velocity.py

from Tkinter import *

root = Tk()

root.geometry("%dx%d+%d+%d" % (480, 540, 10, 10))

canvas = Canvas(root, bg='green')

canvas.pack(fill=BOTH, expand=1)

class Cv():
    x = 0
    y = 0
cv=Cv()

canvas.create_oval(50,50,100,100,fill="orange",tag="ball")

def mv():
    x = cv.x * 0.02
    y = cv.y * 0.02
    cv.x -= x
    cv.y -= y
    if max(cv.x,cv.y) < 0.5:
        cv.x = 300
        cv.y = 400
        canvas.delete("ball")
        canvas.create_oval(50,50,100,100,fill="orange",tag="ball")
    canvas.move("ball", x, y)
    canvas.update()
    root.after(1, mv)

mv()
root.mainloop()