How does a skateboard prevent damage when jumping off a high ledge but without it, you’d probably hurt something?
In: 6
Because it has wheels, allowing you to roll down a ramp, gently redirecting your downward force in a different direction.
If you mean just a high ledge, forward momentum helps. Watch a free runner, they can make the same high drops using forward momentum and a roll. The board also absorbs a small amount of the impact.
It does still hurt. You will notice skateboarders will use their quadriceps and knees to absorb the vertical kinetic energy built up by the fall as well as the wheels and board as a very small bit of cushion, and they don’t trip because the horizontal momentum is mostly maintained in the landing.
This is coming from an engineer who used to skate a lot, but I’m really not 100% positive if my intuition on this is correct. I’m sure someone will come in and roast me on this lol.
Force = mass X acceleration
Force here is how badly you get hurt.
Mass is how much you weigh.
Acceleration is how quickly you change speed. In the case of jumping, how quickly you go from falling to a total dead stop on the ground.
Since you can’t magically change how much you weight in an instant, the only thing you can do to reduce the force you land with is to increase the amount of time it takes you to go from moving to being stopped.
The trucks and wheels on a skateboard do just that. They compress a little bit which slows your change of speed down. It’s not a huge amount but it can be enough to mean the difference between getting hurt and being ok.
I think a big part of it is the people you see doing those tricks have been practicing every day for years to slowly increase the amount of steps they are capable of jumping down. People who fall from similar heights are panicked with no practice so they get hurt. I bet without the board, if you practiced from a low height and slowly increased it, you’d probably be able to achieve a similar drop without injury.
You know how they say “it’s not the falling that hurts, it’s the sudden stop at the end”?
While there is some impact, the skateboard allows for the downward momentum to be converted to horizontal movement. As a result, there isn’t a sudden stop.
It doesn’t prevent the damage and it only contributes a negligible amount of cushioning (unless one lands on the wrong part of the deck and it snaps, which would absorb some of the energy). Skaters get hurt and bruise their heels on a regular basis, and more serious injuries are also common. Impact dispersing shoes and insoles are also very popular in skating for this reason (and they tend to become more popular when doing huge stairsets/drops becomes trendy).
Skateboarders rely on their leg muscles and a lot of practiced technique to crouch and absorb the impact as they land. They have to do so while landing straight and keeping their balance so they can roll away and not slide out and lose control. If they do not roll away from it on the skateboard successfully, they will often be forced to try and run or dive roll out of it to try and absorb the horizontal momentum they had.
The approach speed (and therefore horizontal momentum) is really only needed to clear whatever object you’re trying to jump over (commonly stairs). It also helps to have some speed when rolling away, as it makes it less likely that a small crack or other obstacle will catch your wheels enough to jar you off-balance, which happens easily if you’re moving at a crawl.
If you land and roll away you have to deal with the expected vertical force of landing and that’s it.
If you lose the skate, you have to deal with your forward momentum too, which may be quite big.
So you have to absorb the vertical hit plus horizontal hit and your body was set in a position for the vertical hit only. You touch the ground and your feet are stuck by the compression while your body keeps going forward; you end up having to roll your body on the floor, and it takes time to learn that, the first times you get a lot of bruises. You can easily break an ankle trying to compensate last second. The later you realize you are landing on foot the worse it is.
In parkour you jump with a plan already, all forces accounted for. And of course, having no wheels means you can’t land at skateboard speeds. You gonna jump with less speed and land with less speed. Vertically, you have more room to absorb impacts without a skateboard (you need energy and leg/ankle extensions to be used to control the board, to be subtracted from what you have available to absorb the landing), result is you can land higher jumps without a skate.
Source: engineer and former skateboarder.
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