Algodoo

Wohoo! Look at it going! To make it go up fast, press "up". To brake (if you do, you spoil the fun!) press "enter". To go down faster, press "down". Warning! Stop pressing "up" before you hit the top, that makes it break. For best results of down going, let it freefall. If you press "down", brake seconds before you hit the ground. Thanks!

PS: I made this with my friend.