Yes and no. A topspin ball's flight path bends down and so impact on the table is more vertical. More downward force on impact means more upward force on rebound. Higher bounce. It's true that the topspin itself causes the ball to jump forward (not upward) on impact, and get to the top of the bounce and dip down faster if there's enough residual topspin.
Thanks for your response! I've update parts of the post.
1) The explanation I provided was similar to Wikipedia's "intuitive" explanation, and I thought it was easy to visualize, so I will leave it as is. I'm not great at physics, so I will defer to you what a more appropriate explanation would be.
2) I was making the assumption (that I agree is not always correct) that the speed of the shot would more be limited by concern of the ball landing outside the table than limited raw strength from the player.
3) I've updated the post to state that topspin is associated with bouncing upward and forward instead of causing the ball to jump upward and forward
Your logic sounds good but you forget that the ball still has top spin which makes it want to drop. On top of that the ball shoots out after the bounce if the tangential speed of the surface of the ball is faster than the speed of the ball. The ball leaves the table at a shallower angle.
Excuse me, why do you write an article on a matter you don't have the competence to deal with, addressed "to those who are unaware of" ?Brokenball made the very right corrections,and you have corrected,but at the same time you made the corrections just because " I'm not great at physics, so I will defer to you what a more appropriate explanation would be."Just imagine what would be the result if you were corrected not by the competency of Brokenball, but of some one else, even more incompetent than youIf that was just a forum thread, than OK, its a matter of discussion.But you write an article for a public net consumption, expected to be believed as true by all readers.Sorry for the sharp and negative response, but You have to be more responsible when you try to teach the others.
Interesting contention. You may be right (I haven't done the math) but I'm skeptical. For argument's sake I'll assume you're saying that more topspin always causes the ball to leave the table at a shallower angle, i.e., it doesn't bounce as high. Consider two balls with equal energy, a loop (more topspin, less speed) and a drive (less topspin, more speed). You say the drive always bounces higher than the loop. In other words, after the loop bounces, the increased upward force of the more vertical impact is always dominated by the increased downward force of the Magnus effect. But doesn't this depend on trajectory? So for example a sufficiently curved loop will bounce higher than a sufficiently flat drive of equal energy. Is this wrong? Maybe you can't get sufficiently curved vs sufficiently flat with the same energy. Have you done the math?
ZIGZAG BALLS
This is the most amazing aerodynamical effect one can get on some occasions when playing table tennis with some specific strokes. Moreover, wobbling (Zigzag) balls can be generated manually on purpose, with the help of a physical theory of zigzag balls as worked out by a Russian jet-missile engineer, a guy really keen on the game.
Be happy.
https://sun9-53.userapi.com/TwEjiBIck8aQ8lf4y4kwQ0IzEuQm28WSvY39ag/BrtY4IbxHJg.jpg
I might but there is the Magnus effect, coefficient of restitution, and air friction.
Given the same angle of incidence, yes.
The ball will only bounce up at about 90% of its impact speed if there is no spin.
No argument there. But the point is the loop usually has a steeper angle of incidence because of the extra topspin. So -- unless the Magnus effect of the post-bounce topspin always dominates the extra upward force of the more vertical impact -- the loop can bounce higher. Sure seems to me like slower curvier loops tend to bounce higher than faster flatter drives. Could be wrong, could be they're slower and tend to land shorter on the table and so have more time to reach the top of the bounce, or some other factor. But I'm still skeptical. On the other hand, I have no doubt that flat trajectory heavy topspin loops (and fast serves) stay low and dip lower. Clearly in that case, because of the shallow angle of incidence, the Magnus effect dominates post-bounce.
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broken ball
So a question for you. If you just use your hand to toss a TT ball without spin so it barely goes over the net and then land's on the other side, how long does that take? You may ignore air resistance. Your answer will be close enough. The net is 165.25 cm high. Assume the bottom of the ball reaches a height of 16.3 cm to barely go over the net.
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Not sure the point of your question. Free fall time from net height without air resistance is a little under a fifth of a second. If I hand toss a ball so it reaches maximum height as it skims over the top of the net, time of flight will depend on how far away from the net I was standing when I tossed the ball. However, the height of the bounce won't change depending on distance of flight. Maybe that's your point. But height of bounce will change depending on maximum height of the trajectory.
Edit: Okay, I think I get your point. You're saying that if the loop and the drive have the same maximum height over the table, the loop (with more topspin) will bounce lower. That I agree with. But if they have the same energy, the loop will usually be loopier (higher maximum height) and so will bounce higher unless the post-bounce Magnus effect dominates.
Yes, but also the direction of the brushing motion. This is very important because the ball can be hit at the same place but get different spin depending on the brushing ( tangential ) motion of the paddle relative to the ball.
No, I haven't seen any evidence that change the axis of spin. That would take an external force other than the air.
This is an assumption. I do agree you are right in some cases but not all. I like to make slow spinny loops at angles and there must be more arc to land the ball on the table near the side edge. This is an example of where the angle of incidence may be higher with a loop but then this shot is not even possible with a flat hit. I think it is better to compare long balls that bounce close to the edge of the table because this is possible with both flat hits and loops but the loops can be hit from a lower position whereas a flat hit must have a line of sight and the ball is actually hit into the table as opposed to a good loop where the ball is dropping only due to gravity and the Magnus effect.
This is why I bring up the Sakai video. The Magnus effect does dominate but that is an extreme case.
From my experience, this is not the case. I have played choppers where I must match the spin of the ball or add some to be more aggressive but since I am not a pro, the ball go over the net without much speed but they do drop causing the chopper to move forward to get to the ball.
By all means be as skeptical as you want. I encourage it. I have always been skeptical and questioned everything. Your question is good but we need an apples to apples comparison.
Yes.
So how does Sakai serve a ball that goes from his end of the table to the other end of the table in about 0.24 seconds?
Could not agree more: I've been writing for local newspapers before the ineternet era, as I was considered being a "music expert", the chiefs editors I had to deal with were very clear with me: finding sources isn't the only sufficient matter, you have to 1- verify them 2- understand them 3- rendering/making them inteligible/understandable. If one is missing, the others are comprommised. You did not understand the source, then you were not able to make it inteligible. I think this is very serious. Intellectual integrity should matter first way before searching for fame. That's the problem nowadays with internets and social medias: hierarchical information does not exist anymore, anyone can write BS and be considered an expert, see what's happenning nowadays with rejection of science about the pandemic and vaccines.
Cheers BB,
No one mentioned the Bernoulli principle. The formulas are quite different.
Hence dimples on golf ball. If you watch the better drivers at the range you can see the angle of the trajectory of the ball often increases due to back spin and the dimples. TV golf programs show this effect a lot because the pros are driving the ball.
Could this be like applying reduced mass to TT impacts?
