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Falling Ladder

  1. Jul 22, 2011 #1
    Last edited by a moderator: Apr 26, 2017
  2. jcsd
  3. Jul 22, 2011 #2
    you mean can a ladder fall from such a height and be expected to land in the ground? i dont think so.
     
  4. Jul 22, 2011 #3

    Pythagorean

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    RK, I think he means climbing up to reduce the downward speed, thus reducing the hitting force at ground level

    It would depend on the inertia of the object you're pushing off of (assuming you're in the same reference frame as it). If the object has a lot of inertia, pushing off of it right before you hit the ground will work against your hitting force a bit, but there's no guarantee it will be enough. If the object doesn't have much inertia (like if you pushed off of a penny) the penny would just fly away from you and you wouldn't move at all (within your falling reference frame, that is).

    I've always imagined doing this in a falling elevator, pushing off right before it hit. I don't know if it would be enough, though. You could do the calculations though if you estimated the impulse of a human pushing off of a heavy object, assuming the person had already fallen some X feet in the elevator, gathering speed at 9.8 m/s per second. Maybe somebody is bored enough to try.
     
  5. Jul 22, 2011 #4

    berkeman

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    No, it's just a cartoon.

    Except the PP was climbing down when the ladder hit.... Good thing it's just a cartoon! :smile:
     
    Last edited by a moderator: Apr 26, 2017
  6. Jul 22, 2011 #5

    Pythagorean

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    expectation dyslexia =/
     
  7. Jul 22, 2011 #6
    Yeah, I think it is possible, too.

    Not by climbing down, though, but by climbing up.

    The thing is that you have to time it just right and you need another object to jump to other than the ground since you have to jump off before the ladder hits the ground. In other words, the center of mass of you and the ladder will continue to fall at the same rate whether the you climb the ladder or not...if you are fast enough (unlikely) and the masses are right, you could climb the ladder rapidly to the point where your speed is nearly zero and at that time jump off to a non-moving surface, like the roof of the building conveniently next to you.
     
  8. Jul 22, 2011 #7
    The Myth Busters did this one, the elevator, not the ladder. Their conclusion was that a person couldn't jump upward with enough velocity to usefully reduce the impact. A ladder wouldn't have nearly enough inertia to slow you down, but you would speed up the ladder by climbing it.
     
  9. Jul 22, 2011 #8

    Pythagorean

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    Probably depends on the falling height. If you could model damage as a function of falling height, you might be able to find a critical starting height for which it's worth it.

    With a stick ladder, there wouldn't be so much ladder climbing as mich as pushing the ladder down
     
  10. Jul 22, 2011 #9

    berkeman

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    And with that intelligent response, this cartoon thread is closed.
     
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