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Hamburgr t1_ir35cbd wrote

Reply to comment by herrscherofchicken in what goes around comes around by sometimesisleeptoo

Late to this is post, but look carefully at his legs. He's not "jumping", he merely retracting his legs toward his body and it gives the illusion of jumping. As someone else pointed out, momentum does the rest.

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ignaloidas t1_ir3w9ot wrote

It is jumping. Merely retracting your legs would send you straight into the wall. Defining newtonian principles in a centrifugal system is somewhat unintuitive, but you do need to exert force upon the skateboard to go around the rails.

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Hamburgr t1_ir3xfvq wrote

He would go straight into the wall if he continued in his path for a significant part of the curve. This is obviously an approximation, but he's only in free motion for like 3-5 degrees of a circular arc. That's not a lot in the grand scheme of things. After which, his feet are back on the board and he receives the necessary centrifugal force again to get back in the path of the arc.

Edit: Keep in mind that he keeps his current velocity vector when his feet leave the board. The absence of his feet on the board doesn't mean he suddenly gets sucked into the wall (where would that force come from?)

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ignaloidas t1_ir4c02x wrote

Inertia is carrying him into the wall, as there is no force that's holding him away from it. Without any velocity into the wall he wouldn't be able to ride it.

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Hamburgr t1_ir4vieh wrote

We agree that motion would be similar to releasing a ball that you are spinning in a circle by rope. When released, it continues with the instantaneous tangential velocity at that moment. However, the skateboarder's center of mass (lower torso) is somewhere on the order of 2.5 to 3 feet away from the ramp surface. Fundamentally his circular path of motion is offset from the ramp surface. Over course of his free motion from release to re-contact, he's only in the air long enough for his center of mass to get closer to the wall by like 3ish inches. Therefore, he can clear the ladder and quickly get back to the board before hitting the ramp wall.

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mattswingen t1_ir4kjdt wrote

You’ve never tried a hippy Jump on a skate board. try exerting force onto the thing which requires constant momentum moving forward. If you exert down and backwards force it’s already over. And the board is gone.

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mattswingen t1_ir4kpxp wrote

You carry an insane amount more force than that board so you have to detach, not jump.

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