Bouncing Ball Simulator - AG

import turtle
import random

wn = turtle.Screen()
wn.bgcolor("black")
wn.title("Bouncing Ball Simulator")
wn.tracer(0)

balls = []

for b in range(30):
    balls.append(turtle.Turtle())

colors = ["magenta", "cyan", "orange", "yellow", "hot pink", "lime"]
shapes = ["circle", "triangle", "square"]

for ball in balls:
    ball.shape("circle")
    ball.color(random.choice(colors))
    ball.penup()
    ball.speed(0)
    x = random.randint( -   290, 290)
    y = random.randint(- 290, 290)
    ball.goto(x, 200)
    ball.dy = 0 #how high up the y axis the ball bounces
    ball.dx = random.randint(-3, 3)
    ball.da = random.randint(-5, 5)

gravity = 0.1 #Gravity motion on ball

while True:
    wn.update()

    for ball in balls:
        ball.rt(ball.da)
        ball.dy -= gravity #Ball speeding up as it falls
        ball.sety(ball.ycor() + ball.dy)

        ball.setx(ball.xcor() + ball.dx)

        if ball.xcor() > 300: #where does ball bounce on x axis
            ball.dx *= -1
            ball.da *= -1

        if ball.xcor() < -300: #where does ball bounce on other side of x axis
            ball.setx(-300)
            ball.dx *= -1
            ball.da *= -1

        if ball.ycor() < -300: #where does the ball bounce on y axis
            ball.sety(-300)
            ball.dy *= -1
            ball.da *= -1