1D Springs

from tkinter import *
import random
import time
import math
tk=Tk()
WIDTH=500
HEIGHT=400
canvas=Canvas(tk,width=WIDTH,height=HEIGHT)
tk.title('Spring')
canvas.pack()

dt=.0001
k=1000
mass=1
length=40
num=10

class Ball:
    def __init__(self,pos):
        self.shape=canvas.create_oval(pos,100,pos+10,110,fill='blue')
        self.vel=0
    def move(self,left,right,i):
        acc=k*(right-pos-length)-k*(pos-left-length)
        self.vel+=acc*dt
        #if i==0:
            #self.vel=0

        canvas.move(self.shape,self.vel*dt,0)
        
        

balls=[]
for x in range (num):
    balls.append(Ball(x*50+100))

for x in range(100000):
    for i in range(len(balls)):
        if i==0:
            left=canvas.coords(balls[i].shape)
            left=left[0]-length
        else:
            left=canvas.coords(balls[i-1].shape)
            left=left[0]  
        if i==len(balls)-1:
            right=canvas.coords(balls[i].shape)
            right=right[0]+length
        else:
            right=canvas.coords(balls[i+1].shape)
            right=right[0]
        pos=canvas.coords(balls[i].shape)[0]
        balls[i].move(left,right,i)
    tk.update()


    
    
tk.mainloop()