The Projectile Cart

The QuickTime movie below shows a small cart moving from left to right at constant velocity. As it moves it fires a projectile vertically from the "cannon" mounted on the cart. What happens to the projectile? Does it land behind the cart? No! It lands back in the cannon!

The cart, cannon, and the ball share the same velocity before the "cannon" is fired, since they are moving along together. As the ball moves, it keeps the horizontal velocity that it had before it was fired. Use the arrows to view the movie frame-by-frame, and note the horizontal positions of the ball and the cannon as the ball moves through the air.

last updated March 3, 2000 by JL Stanbrough