[VISIBLE ONLY LOCALLY] Optionally view what the website will look like at another time (in PDT):
Credit: Problem written by Chris.
Handouts: Graphics Reference
Make a ball that bounces as if under the influence of gravity. To do this, adapt code for a regular bouncing ball, but each frame have the y velocity increase downward by a small amount to simulate the pull of gravity. Additionally, each time the ball bounces off the bottom, decrease the y velocity by a certain percentage.
(Note: the gray path in the image above is just an illustration - the working program will just have a black ball bouncing on the screen)
""" File: gravity_ball.py ------------------- A ball bounces as if due to gravity. Specifically, each frame the y velocity increases downward to simulate gravity, and each time it bounces it loses some of its y velocity to simulate damping. """ import time from graphics import Canvas BALL_DIAMETER = 20 ANIMATION_DELAY_SECONDS = 0.02 # The amount to add each frame to the y velocity to simulate the pull of gravity GRAVITY = 0.5 # The amount by which to multiply the y velocity each time we bounce (simulates losing energy) DAMPING = 0.7 def main(): canvas = Canvas() canvas.set_canvas_title("Gravity Ball") # draw a ball on the top left corner ball = canvas.create_oval(0, 0, BALL_DIAMETER, BALL_DIAMETER) canvas.set_color(ball, "black") # variables for velocity vx = 3 vy = 0 while True: # update vy vy += GRAVITY # should the ball bounce? if (canvas.get_top_y(ball) > (canvas.get_canvas_height() - canvas.get_height(ball))) and vy > 0: # Dampen the velocity and invert the velocity vy = vy * -DAMPING canvas.move(ball, vx, vy) time.sleep(ANIMATION_DELAY_SECONDS) canvas.update() canvas.mainloop() if __name__ == "__main__": main()