Some scientific analysis of Mao's 3A

[Blades of Passion]

That number for Mao is not correct at all. I'd say she is twice that distance off the ground. Did someone forget to multiply by 2 somewhere in the equation?

 

[gsrossano]

That number for Mao is not correct at all. I'd say she is twice that distance off the ground. Did someone forget to multiply by 2 somewhere in the equation?

No. Did not forget. I too am amazed she only gets 10 inches off the ground and 0.45 seconds in the air. 18 inches would put her about 0.6 seconds in the air.

(Typical Jun/Sen men are 0.6 - 0.75 seconds in the air. Typical Jun/Sen Ladies are 0.4 - 0.6 seconds in the air.)

 

[Blades of Passion]

It is important to believe our eyes and brains, not just what is written.

She jumps higher than that.

 

[gsrossano]

She jumps higher than that.

Prove it. Ikegami has a measurement. You have an opinion.

 

[hurrah]

No where in the original article is there any mention of the height that Mao reaches when she jumps, so this 10-inch figure is a myth invented on this very thread.

Also, it is important to take careful note of Ikegami's statement and the interpretation of the journalist.

In the article, Ikegami apparently said that Mao at 15 spent 0.55 seconds in the air, while Mao now spends 0.45 seconds in the air, so she is now rotating more quickly than when she was younger.

It is the journalist who then adds commentary:

回転数の多いジャンプには （１）高く跳んで滞空時間を稼ぐ走り高跳びタイプと、 （２）助走速度を上げて速く回転する走り幅跳びタイプ、に分かれるという。単純計算で、浅田が１回転に要する時間は０秒１７と （２）のタイプとして、ほぼ完成形に達している。

translation:

It is said that jumps of many rotations can be divided into (1) the type jumped by those who procure air duration by jumping high into the air, and (2) the type jumped by those who increase run-up speed into the jump and thus are able to rotate quickly in the air. In simple calculation, Asada takes 0.17 second per rotation and thus can be considered type (2) jumper, and this is how she has perfected her technique.

I think this journalist knows less than those who write in Golden Skate Forums.

I personally think Mao is the kind of jumper who jumps high into the air and rotates quickly. For comparison, I think Yuna jumps high and wide but does not rotate as quickly. Miki also jumps high and wide but not as wide as Yuna, while rotating more quickly than Yuna but not as quickly as Mao.

 

[Blades of Passion]

Prove it. Ikegami has a measurement. You have an opinion.

Measure the height of a rink wall. Pause the video and look at how high Mao's feet are off the ground.

 

[janetfan]

Measure the height of a rink wall. Pause the video and look at how high Mao's feet are off the ground.

Here is Mao's LP from WTT.
If you freeze this at 28 seconds - it appears she is more than 10 inches off the ice.

http://www.youtube.com/watch?v=SWAK5LPF7Qo


Not scientific and just using my eyes - but it is hard to believe this 3A has barely left the ice as the "professor" claims.

 

[schiele]

I wish I had paid closer attention while seeing it live in October. I remember I thoguht the height she was getting on those jumps was ok (not bad but not great) but her 2 Axel was big (I guess this is normal compared to other girls since she can do 3 Axels). Nevertheless I definitely thought she rotated those 3 Axels like a tornado.. Actually I definetely remember thinking so that's how she gets around them. I don't know about 10 inches, I am just talking comparatively to other girls and other 3 axels by men..

 

[silverlake22]

I wish I had paid closer attention while seeing it live in October. I remember I thoguht the height she was getting on those jumps was ok (not bad but not great) but her 2 Axel was big (I guess this is normal compared to other girls since she can do 3 Axels). Nevertheless I definitely thought she rotated those 3 Axels like a tornado.. Actually I definetely remember thinking so that's how she gets around them. I don't know about 10 inches, I am just talking comparatively to other girls and other 3 axels by men..

ITA. Mao's jumps in terms of height are in the middle of the pack, a lot of ladies jump higher than she does, but a fair amount also have smaller jumps. That being said, Mao definitely rotates very quickly, and tightly. Her jumps do not travel horizontally hardly at all whereas the jumps of Yuna and Miki travel quite some horizontal distance.

 

[gsrossano]

No where in the original article is there any mention of the height that Mao reaches when she jumps, so this 10-inch figure is a myth invented on this very thread.

The time in the air and the height of a jump are directly related. You can calculate one from the other. This is knowns as physics, not a myth.

It is said that jumps of many rotations can be divided into (1) the type jumped by those who procure air duration by jumping high into the air, and (2) the type jumped by those who increase run-up speed into the jump and thus are able to rotate quickly in the air. In simple calculation, Asada takes 0.17 second per rotation and thus can be considered type (2) jumper, and this is how she has perfected her technique.

0.17 per rotation is not consistent with 0.45 seconds in the air for a 3A. 0.17 per rotation is 5.9 rotations per second. In 0.45 seconds that would give you 2.7 rotations, which is not the 3.5 needed for 3A. At 0.17 rotations per second you would need 0.6 seconds to complete 3A. So the article seems to be a bit confused.

6 rotations per second IS fast rotation, but I don't think skaters can be divided into a low rotation group and a seperate high rotation group. Among a large group of skaters the rotation rate spans a large range with no gap in between. There are slow rotation jumpers and high rotation jumpers, but there are also middle rotation jumpers.

Measure the height of a rink wall. Pause the video and look at how high Mao's feet are off the ground.

No. This is not a good way to do it, as you do not know the height of the wall from the video. Nor do you know the distance the skater is from the wall, or the location of the camera and the associated perspective.

What you could do (you, not me!) is isolate the frame where she leaves the ice and the frame at the top of the jump and measure the vertical displacement relative to the height of the skater. If you knew her height you could then get the height of the jump. But this requires the distance from the skater to the camera remain constant during the jump. If the skater is moving towards you or away from you it doesn't work.

What you could also do from the video (still you, not me!) is try to determine the frame rate for the video, then step through the jump one frame at a time and find the frame the instant she leaves the ice, and the frame the instant she lands. This will tell you the time in the air. From that you can calculate the height of the jump and also the average rotation rate. You could get the frame rate from the total number of frames in the video clip and the total time indicated for the full video clip. Some video clips also include the frame rate in the metadata, if you can get to it.

After you do this experiment and have real numbers, please post them. Would love to see your results.

 

[Blades of Passion]

Okay, this is what you're sounding like right now:

http://www.youtube.com/watch?v=82py_wk5vE4

Of course it's not going to be exact by looking at a video and comparing to the height of the rink wall; the perspective distance of the camera causes variances. However, we can do a fairly accurate estimation with our eyeballs. It's plain to see Mao jumps higher than 10 inches.

I have seen her live too and been right there with here at rink level.

If Mao jumps 10 inches off the ice then I must be 3 feet tall rather than 5'11''.

 

[gsrossano]

We have a saying where I work. "In God we trust. All others bring data." So far you still only have opinion and impressions from an uncalibrated video and NO DATA. Think what you want. It is still only what you think and not a measurement.

 

[Mathman]

No where in the original article is there any mention of the height that Mao reaches when she jumps, so this 10-inch figure is a myth invented on this very thread.

Here is the formula: Seconds squared times 4 = height in feet.

It is utterly impossible for any object in free fall to escape that formula. You can derive it by knowing that the acceleration due to gravity near the surface of the earth is -32 ft/sec^2. When this astonishing fact was discovered by Galileo, it utterly overturned Aristotian physics that had dominated Western thought for 1500 years.

It is extremely unlikely that a serious researcher, a professor of biometrics at a prestigious university, would measure these parameters incorrectly.

As for "believing our own senses," they are easily decieved. (An unigested bit of beef, a blot of mustard. ) That is why we have scientific measuring devices.

It is widely believed that Michael Jordan had greater hang time than anyone else, about one full second (= four feet above the floor). Studies showed that this was exaggerated. What Jordan could do, however, was draw his legs up to give the illusion that he was hanging in the air for a long time..

Male ballet dancers can to this, too. By redistributing their arms and legs around their center of mass in mid-flight, they can create the illusion of being suspended in mid-air at the peak of their jump.

 

[janetfan]

Here is the formula: Seconds squared times 4 = height in feet.

It is utterly impossible for any object in free fall to escape that formula. You can derive it by knowing that the acceleration due to gravity near the surface of the earth is -32 ft/sec^2. When this astonishing fact was discovered by Galileo, it utterly overturned Aristotian physics that had dominated Western thought for 1500 years.

It is extremely unlikely that a serious researcher, a professor of biometrics at a prestigious university, would measure these parameters incorrectly.

As for "believing our own senses," they are easily decieved. (An unigested bit of beef, a blot of mustard. ) That is why we have scientific measuring devices.

It is widely believed that Michael Jordan had greater hang time than anyone else, about one full second (= four feet above the floor). Studies showed that this was exaggerated. What Jordan could do, however, was draw his legs up to give the illusion that he was hanging in the air for a long time..

Male ballet dancers can to this, too. By redistributing their arms and legs around their center of mass in mid-flight, they can create the illusion of being suspended in mid-air at the peak of their jump.

Interesting post - but what in the world did Newton and his "apple plonking the noggin" theory measure? Something about the laws of gravity?

Or was it more along the lines of the old "what weighs more: a ton of bricks or a ton of feathers?"

 

[Blades of Passion]

We have a saying where I work. "In God we trust. All others bring data." So far you still only have opinion and impressions from an uncalibrated video and NO DATA. Think what you want. It is still only what you think and not a measurement.

If I am 6 feet tall and someone jumps on top of my head, they have jumped 6 feet.

I have seen Mao jump directly in front of me, in real life. She jumps more than 10 inches.

If she were really jumping that low, then it means her jumps would be reaching a height that is lower than my knees...and that is just completely false.

 

[Mathman]

Interesting post - but what in the world did Newton and his "apple plonking the noggin" theory measure? Something about the laws of gravity?

To quote Sir Isaac himself, "If I have seen further it is only by standing on the shoulders of giants." The giant in question was Galileo.

Galileo discovered that all objects fall at the same rate, regardless of mass and composition. What Newton discovered was the inverse square law of gravitation. The point of the apple story is that Newton realized that the same natural law that governs the fall of an apple from a tree also determines the orbits of the moon and planets.

Newton's theory of gravity held up well for a long time (not as long as Aristotle's, though). It was superceded in 1917 by the ideas of Einstein.

 

[Phoenix347]

Newton's theory of gravity held up well for a long time (not as long as Aristotle's, though). It was superceded in 1917 by the ideas of Einstein.

However, figure skating jumps doesn't even remotely approach relativistic velocities so I would think Newton's laws are still very valid when it comes to figure skating.

 

[FlattFan]

The equation to see how high her jumps are is

X = Xo + Vo*t + 1/2*a*square(t) with
a = 9.8 m/square(sec)

Assuming t_total = .45s, and assuming Mao jumps up and down in the exact same spot (i.e. no traveling), she's only .248 m above the ground, which translates to roughly 9.6 in.

I'm almost certain Mao does not jump up and down on the same spot. So her max height is 9.6 in and her actual height is 5 in.

The point is, I highly doubt t = .45s. Seems bogus.

Her jumps seem to last more than a second just like those long jumpers who are definitely on air for longer than a sec.

 

[Phoenix347]

I just jumped in my room and the bottoms of my feet were at least 11 inches (height of the notebook next to the wall) off the ground from a stand still. I'm not an Olympic caliber athlete so I would have to assume that Mao can jump way higher than me. 10 inches does seem a bit low.

Edit: I have to admit I was not wearing figure skates when I jumped nor was the surface ice.

 

[Mathman]

I'm almost certain Mao does not jump up and down on the same spot. So her max height is 9.6 in and her actual height is 5 in.

The actual height is still 9.6 inches regardless of the horizonal distance.

The "v0" in your formula is the verticle component of the initial velocity. If v1 is the horizontal component, then the distance is simply d = v1t. If you want to maximize your horizontal distance, aim for a 45 degree angle of take-off.