Freeskiing - Tricks over Jumps


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Abstract:
For this exploration, I will be looking closely at a skier's speed in relation to jump size as well as how much a skier needs to "throw their body" in order to complete specific tricks. To do this, I will have to estimate the angle at which the skier's shoulders are as the wind up for a trick.

Guiding Question

I initially wanted to know how spesific tricks were completed based on a skier's movement in the air and the type of axis they are on, but that became too difficult. Now I want to know how a skier's speed and the angle at which they set their shoulders before they leave the lip of the jump has an effect on spesific tricks.

Hypothesis/Prediction

Throghout this project, I expect to observe the effects of the conservation of angular momentum. I think that the more complicated the trick or the more rotations, the greater the conservation of momentum will be. This is because when there are no external forces producing torque about the axis of rotation, the skier’s angular momentum will remain constant. When a skier is rotating in the air after going over a jump, their angular momentum is conserved. This means that however much angular momentum they generated during take-off, they cannot change the angular momentum in the air. This means that skiers have to generate a specific amount of angular momentum to complete specific tricks or rotations in the air. Thus as stated above in the second sentence, I predict that the more complicated the trick, the more conservation of angular momentum there will be.

New hypothesis:
Since I decided to focus in on a different aspect of how tricks are completed over jumps, I have developed a new hypothesis/prediction. I predict that the larger the jump, the more speed a skier will need. And I also predict that the more complex a tricks is (defined by number of spins and axis rotation), the more a skier will have to wind up and throw their body when they leave the lip of the jump.


Experimental Procedure


Interim Evaluation: May 3


Week of May 3 – May 9: Data Collection, Analysis, update WeSee page

Week of May 10 – May 16: Data Collection, Analysis, update WeSee page

Week of May 17 – May 23: Compile Analyses and update WeSee page

Week of May 24 – May 30: Post all data collection and analyses to this WeSee page

Week of May 31 – June 6: Continue to post all data collection and analyses to this WeSee page and prepare for final product of project / prepare for presentation of project


Project due: June 8


Experiment/Data/Analysis


Nick Martini straight air

Jump size: 65 foot step down


1.6 seconds - 1.505 seconds = .095 seconds
1.71 meters / .095 seconds = 18 meters/second

Straight_Air_video.jpg
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180 data

Jump size: 10 foot table top

0º
4.641 seconds - 4.475 seconds = .166 seconds
1.71 meters / .166 seconds = 10.3 meters/second

180.jpg

180_video.jpg
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360 data

Jump size: 10 foot table top

0º, 5º
31.626 seconds - 31.460 seconds = .166 seconds
1.71 meters / .166 seconds = 10.3 meters/second

360.jpg
360_video.jpg
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540 data

Jump size: 35 / 40 foot table top

0º, 20º/25º

1.873 seconds - 1.74 seconds = .133 seconds
1.71 meters / 1.33 seconds = 12.867 meters/second

Stept_nose_540.jpg
Stept_nose_540_video.jpg
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Ben Moxham flat 360 data

Jump size: 35 / 40 foot step down
0º, 5 º
11.978 seconds - 11.845 seconds = .133 seconds
1.71 meters / .133 seconds = 12.857 meters/seconds


B_Mox_flat_3_pos_vs_vel_graph.jpg

B_Mox_flat_3_video.jpg
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Ben Moxham flat 540 data

Jump size: 35 / 40 foot step down

0º, 2 º, 0º, 10º
8.910 seconds – 8.776 seconds = .134 seconds
1.71 meters / .134 = 12. 761 meters/second


B_Mox_flat_5_pos_vs_vel_graph.jpg
B_Mox_flat_5_video.jpg
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Mike Mertion flat 540 data

Jump size: 40 / 50 foot step down

0º, 20º
4.771 seconds - 4.671 seconds = .1 seconds
1.71 meters / .1 seconds = 17.1 meters/second

Mike_M_flat_5_pos_vs_vel.jpg

Mike_M_flat_5_video.jpg
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Sean Jordan rodeo 540 data

Jump size: 35 / 40 foot step down

0º, 2º, 0º, 10º

12.046 seconds - 11.911 seconds = .135 seconds
1.71 meters / .135 seconds = 12.667 meters/second
Sean_Jordan_rodeo_5_pos_vs_vel_graph.jpg

Sean_Jordan_rodeo_5_video.jpg
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Mike M switch 720 data

Jump size: 40 / 50 foot step down

0º, 30º
12.031 seconds - 11.945 seconds = .086 seconds
1.71 meters / .086 seconds = 19.884 meters/second


Mike_M_sw_7.jpg
Mike_M_sw_7_video.jpg
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Ben Moxham switch cork 720 data

Jump size: 30 / 35 foot table top
0 º, 35 º
15.583 seconds – 15.483 seconds = .1 seconds
1.71 meters / .1 seconds = 17.1 meters/second


B_Mox_sw_flat_7_pos_vs_vel_graph.jpg

B_Mox_sw_flat_7_video.jpg
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Mike Mertion 900 data

Jump size: 35 foot table top

0º, 30º, 0º, 40º
8.408 seconds - 8.275 seconds = .133 seconds
1.71 meters / .133 seconds = 12.857 meters/second

Mike_M_tail_9.jpg

Mike_M_tail_9_video_1.jpg

Mike_M_tail_9_video_2.jpg
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Nick Martini cork 900 data

Jump size: 35 / 40 foot table top

0º, 2º, 0º, 55º
2.275 seconds - 2.141 seconds = .134 seconds
1.71 meters / .134 seconds = 12.761 meters/second

Nick_Martini_cork_9.jpg
Nick_Martini_cork_9_video.jpg
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Ben Moxham cork 900 data

Jump size: 55 / 60 foot table top

0º, 15º, 0º, 45º
24.391 seconds – 24.325 seconds = .066 seconds
1.71 meters / .066 seconds = 25.91 meters/second


B_Mox_dub_cork_9_pos_vs_vel_graph.jpg

B_Mox_dub_cork_9_video.jpg
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Mike Mertion flat 900 data

Jump size: 40 / 50 foot step down

0º, 10º, 0º, 35º
15.516 seconds – 15.416 seconds = .1 seconds
1.71 meters / .1 seconds = 17.1 meters/second


Mike_M_flat_9_pos_vs_vel_graph.jpg

Mike_M_flat_9_video_1.jpg

Mike_M_flat_9_video_2.jpg
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Nick Martini switch 1080 data

Size of jump: 65 foot table top

0º, 55º
3.913 seconds - 3.813 seconds = .1 seconds
1.71 meters / .1 seconds = 17.1 meters/second

Nick_Martini_10_tail.jpg

Nick_Martini_10_tail_video.jpg
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Gus Kenworthy switch 1080 data

Jump size: 45 foot step down

0º,15º, 55/60º
1.436 seconds - 2.336 seconds = .
1 seconds

1.71 meters / .1 seconds = 17.1 seconds


Gus_K_sw_tail_10.jpg
Gus_K_sw_tail_10_video_1.jpg
Gus_K_sw_tail_10_video_2.jpg
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Gus Kenworthy switch double flat 720 data

Jump size: 45 foot step down

0º, 15º,0º, 50º

1.601 seconds - 1.501 seconds = .1 seconds
1.71 meters / .1 seconds = 17.1 meters/second


Gus_K_sw_dub_flat_7.jpg
Gus_K_sw_dub_flat_7_video.jpg
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Gus Kenworthy double falt 900 data

Jump size: 45 foot step down

0º, 20º, 0º, 30º

1.601 seconds - 1.501 seconds = .1 seconds
1.7 meters / .1 seconds = 17.1 meters/second

Gus_K_dub_flat_9.jpg

Gus_K_dub_flat_9_video.jpg
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Ben Moxham double flat 900 data

Jump size: 60 / 65 foot table top

0º, 15º, 0º, 35º
4.438 seconds – 4.338 seconds = .1 seconds
1.71 meters / .1 seconds = 17.1 meters/second


B_Mox_dub_flat_9_pos_vs_vel_graph.jpg


B_Mox_dub_flat_9_video.jpg
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Ben Moxham double cork 1080 data

Jump size: 55 / 60 feet

0º, 40º, 0º, 40º
.799 seconds - .735 seconds = .064 seconds
1.71 meters / .064 seconds = 26.719 meters/second


B_Mox_dub_cork_10_pos_vs_vel_graph.jpg

B_Mox_dub_cork_10_video.jpg
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Mike Mertion double flat 1080 data

Jump size: 60 foot table top

0º, 35º, 0º, 50º
22.656 seconds - 22.590 seconds = .066 seconds
1.71 meters / .066 seconds = 25.91 meters/second


Mike_M_dub_flat_10_pos_vs_vel_graph.jpg

Mike_M_dub_flat_10_video.jpg
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Gus Kenworthy double cork 1260 data

Jump size: 45 foot step down

0º, 20º, 0º, 55º/60º
2.603 seconds - 2.503 seconds = .1 seconds
1.71 meters / .1 seconds = 17.1 meters/second


Gus_K_dub_cork_12.jpg
Gus_K_dub_cork_12_video.jpg
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Chart of results:
Trick
Jump Type and Size
Speed (m/s)
Degrees
Nick Martini straight air
65 foot step down
18 meters/second

180
10 foot table top
10.3 meters/second

360
10 foot table top
10.3 meters/second
0º, 5º
540
35 / 40 foot table top
12.867 meters/second
0º, 20º/25º
Ben Moxham flat 360
35 / 40 foot step down
12.857 meters/seconds
0º, 5 º
Ben Moxham flat 540
35 / 40 foot step down
12. 761 meters/second
0º, 2 º, 0º, 10º
Mike Mertion flat 540
40 / 50 foot step down
17.1 meters/second
0º, 20º
Sean Jordan rodeo 540
35 / 40 foot step down
12.667 meters/second
0º, 2º, 0º, 10º
Mike Mertion switch 720
40 / 50 foot step down
19.884 meters/second
0º, 30º
Ben Moxham switch cork 720
30 / 35 foot table top
17.1 meters/second
0 º, 35 º
Mike Mertion 900
35 foot table top
12.857 meters/second
0º, 30º, 0º, 40º
Nick Martini cork 900
35 / 40 foot table top
12.761 meters/second
0º, 2º, 0º, 55º
Ben Moxham cork 900
55 / 60 foot table top
25.91 meters/second
0º, 15º, 0º, 45º
Mike Mertion flat 900
40 / 50 foot step down
17.1 meters/second
0º, 10º, 0º, 35º
Nick Martini switch 1080
65 foot table top
17.1 meters/second
0º, 55º
Gus Kenworthy switch 1080
45 foot step down
17.1 seconds
0º,15º, 55/60º
Gus Kenworthy switch double flat 720
45 foot step down
17.1 meters/second
0º, 15º,0º, 50º
Gus Kenworthy double falt 900
45 foot step down
17.1 meters/second
0º, 20º, 0º, 30º
Ben Moxham double flat 900
60 / 65 foot table top
17.1 meters/second
0º, 15º, 0º, 35º
Ben Moxham double cork 1080
55 / 60 feet
26.719 meters/second
0º, 35º, 0º, 45º
Mike Mertion double flat 1080
60 foot table top
25.91 meters/second
0º, 35º, 0º, 50º
Gus Kenworthy double cork 1260
45 foot step down
17.1 meters/second
0º, 20º, 0º, 55º/60º

I provided pictures from the video I analyzed because most of them show the skier before they hit the jump. You can see arms extended and their body at an angle. This is because they are getting ready to complete a spesific trick and this is exactly what I am measuring (when they are center and at zero degrees to the angle that they wind up their body, then back to zero, to the angle that they are at right before leaving the jump).

The blue dots represent the fact that the camera pans and I had to plot points in order to counteract this so I could achieve a value for the skier's speed. The red dots represent the the skier's speed. For both the blue and red dots, I had to click on a fixed point that would stay constant throughout the video clip. This was easy for the blue dots because I chose a target such as the lip of the jump. However, this was a more difficult for determining the skier's speed because the skier is moving and their whole body is also slightly changing position. This definitely could have had an effect on my results.

Summary and results:
I basically took measurements of the skier's speed and looked at my results in relation to the size of a jump and the type of trick a skier was trying to complete. Certain tricks do not require as much force as others. While my prediction stated that the more difficult the trick, the more a skier will have to "throw their body," this didn't exactly hold entirely true. I forgot when I made my initial prediction, that rotations on a horizontal and vertical axis are much different. This affects how hard a skier must "throw their body." However, I was correct that in the larger the jump, the more speed you will need to clear the knuckle. I found that a skier doesn't always need a ton of speed to complete a spesific trick. A skier can complete spesific tricks based on jump size and this is also something that I knew but forgot to take note of. The larger the jump, the more possibilities a skier has as far as tricks are concerned.


Conclusion

There were a number of things that definitely could have been improved upon in this experiment. I think I chose a difficult concept to focus in on and it gave me a lot of trouble right up until the very end. I also had to deal with poor image quality of the videos in logger pro and as a result, this would definitely alter some of the values on the graphs produced above. In addition, I had to estimate the angle at which the skier "winds up" their body. While this was not 100% accurate, it was as close an estimate that I could possibly guess. One more thing that made this process tricky is that when a skier hits a jump, they are popping and beginning their turn for their rotation all in one fluid movement. Sometimes it is difficult to distinguish how hard they are actually throwing their body because of this. I really don't have any way to measure their force, which will also cause inaccuracy in the angle measurements. And one last thing, I tried my best to get shots that were not in slow motion but I feel like there were a few that were just slightly slowed down (it was hard for me to even tell) so this would definitely alter my values.

My ultimate goal in this exploration was mostly for my benefit and to see if I could figure out how specific tricks are completed so I could one day apply it to my own skiing. However, under the circumstances, I didn't get to explore it the way I would have liked to because it was simply too difficult. However, I did learn about how a skier takes off from the jump for certain tricks because each one is unique in its own way. As far as new questions are concerned, I'd still like to know more about a skier's center of mass and how it correlates to the axis that they rotate on in the air. My result is important to me in that it helps me better understand the mechanics of the sport that I love. I would also like to know how different grabs may affect the difficulty of a trick and if this also affects the skier's speed and how they throw their body. I thought about that throughout this exploration so I think that would have been cool to take into consideration.

Overall, this project had a lot of glitches in it and my results weren't very accurate. I basically had to estimate every single value (degrees, the size of the skis in cm but converted to meters, the skier's speed in meters per second, and even the size of the jumps). I think I essentially took on too much and expected exact values. However, I am happy with my project and I did enjoy working on it. While it doesn't seem too complicated, it was very challenging and I did learn a good amount from it.


Sources



  • 6 pictures at the very top of this page were all found on newschoolers.com



Here are the videos that I used to analyze and pull my data from for this exploration:





























Acknowledgments


Thank you Dr. Pasquini for all of your help and support! I really appreciate it.

Additional information on these sections can be found on the inquiry model page.