Anyone who has ever held a basketball has tossed it up, spun it, and let it bounce on the ground. Don't deny it. You'd watch it bounce back up to you just like you should have. But did you notice how it was spinning? Perhaps you spun it towards yourself, and without noticing after it bounced, I can guarantee it came back up spinning away from you. What sorcery is this? I know you are dying to know, so I'll tell ya.
Optical Illusions are fun! (which way is it spinning?)
First things first, this doesn't only happen with basketballs, but the basketball is a good example.
A basketball is elastic. This means that when it hits the floor, the part of the ball in contact with the floor stops moving momentarily, yet the rest of the ball is still spinning. Consequently, this creates tensions between the two sides of the ball, slowing the rotation down, and storing some elastic energy. When the entire ball stops spinning, this energy will reach its maximum, releasing in the opposite direction while the basketball will leave the ground. And finally, this causes the ball to rotate in the other direction. I think it's crazy that all this can happen in one instant!
Well there ya have it. Your curiosity is cured. You are welcome!
Thanks for tuning in, folks!