I play tabletennis and it is obvious that with top spin, the ball go down faster than the one without any spin. I have try to explain by bernoulli, but it seems the result is opposite: top spin ball will drift more!. Anyone can help?
It is the same as a curveball.
Friction is important. That is why pitchers try to scruff up the ball.
The air flow is slowed down on the top side.
The faster flow on the bottom side reduces that pressure by Bernie's theorem.
Also turbulence at the top increases the pressure there.
Since the ball is rotating in the direction of motion, the friction force on the top surface is much larger than on the bottom surface. But even without that effect, the friction causes the air to rotate around the ball.I agree with you that friction is important. But the force caused by friction isn't up or down is it?.