Python Bouncing Ball Example

import turtle
import random

# Step 1: Getting Started

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

balls = []

for _ in range   (0):
    balls.append(turtle.Turtle())

colors = ["indian red", "light salmon", "orange", "white", "salmon"]
shapes = ["circle", "triangle", "square"]

for ball in balls:
    ball.penup()
    ball.shape(random.choice(shapes))
    ball.color(random.choice(colors))
    ball.speed(0)
    x = random.randint (-290, 290)
    y = random.randint (200, 400)
    ball.goto(x, y)
    ball.dy = 0
    ball.dx = random.randint(-3, 3)
    ball.da = random.randint(-5, 5)

def add_ball(x,y):
    ball = turtle.Turtle()
    ball.penup()
    ball.shape(random.choice(shapes))
    ball.color(random.choice(colors))
    ball.speed(0)
    #x = random.randint (-290, 290)
    #y = random.randint (200, 400)
    ball.goto(x, y)
    ball.dy = 0
    ball.dx = random.randint(-3, 3)
    ball.da = random.randint(-5, 5)
    balls.append(ball)
    print(len(balls))

add_ball(0,0)

gravity = 0.2

wn.onclick(add_ball)

while True:
    wn.update()

    for ball in balls:
        ball.rt(ball.da)
        ball.dy -= gravity
        ball.sety(ball.ycor() + ball.dy)

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

        # Check for a ball collision
        if ball.xcor() > 300:
            ball.dx *= -1
            ball.dx *= -1

        if ball.xcor() < -300:
            ball.dx *= -1
            ball.dx *= -1

        # Step 2: Check for a Bounce
        if ball.ycor() < -300:
            ball.sety(-300)
            ball.dy *= -1
            ball.dx *= -1

wn.mainloop()