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Fixing to External Wall Insulation

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    #32
    GreeBo
    Registered Users Posts: 27,161 ✭✭✭✭GreeBo


    https://www.boards.ie/discussion/comment/120921232#Comment_120921232

    Yep, I've the same one myself!



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    #33
    Lumen
    Registered Users Posts: 31,062 ✭✭✭✭Lumen


    It seems like a junior cert maths question, but what fraction of a 75 degree ladder's weight is exerted against the wall it leans against?

    I'm guessing 1/8th.



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    #34
    hesker
    Registered Users Posts: 1,506 ✭✭✭hesker


    https://www.boards.ie/discussion/comment/120926972#Comment_120926972

    I think It’s just Cos 75 but I usually get these things wrong.

    1/4 roughly?



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    #35
    Lumen
    Registered Users Posts: 31,062 ✭✭✭✭Lumen


    https://www.boards.ie/discussion/comment/120930705#Comment_120930705

    Yeah, but isn't it half that because ...ground something something 😂

    I have no idea.



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    #36
    GreeBo
    Registered Users Posts: 27,161 ✭✭✭✭GreeBo


    and wouldnt it depend on how far up the ladder you stood...?



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    #37
    Pique
    Registered Users Posts: 3,049 ✭✭✭Pique


    I asked ChatGPT: A person weighing 90kg stands 75% of the way up on a 5m ladder weighing 20kg leaning against a wall. How much force is exerted on the wall?

    To calculate the force exerted on the wall by the person standing on the ladder, we need to consider both the gravitational force and the horizontal component of the force due to the ladder.

    Gravitational force on the ladder: The ladder itself weighs 20 kg, so the force due to gravity acting on the ladder can be calculated as:

    Gravitational Force (F_gravity_ladder) = Mass of the ladder × Acceleration due to gravity F_gravity_ladder = 20 kg × 9.8 m/s² ≈ 196 N

    Gravitational force on the person: The person's weight is 90 kg, and the force due to gravity can be calculated as:

    Gravitational Force (F_gravity_person) = Mass of the person × Acceleration due to gravity F_gravity_person = 90 kg × 9.8 m/s² ≈ 882 N

    Horizontal component of force on the wall: The ladder leans against the wall, creating a horizontal component of force on the wall. The horizontal component of force can be calculated as:

    Horizontal Component of Force (F_horizontal) = (1 - Fraction of the ladder length) × (F_gravity_ladder + F_gravity_person) F_horizontal = (1 - 0.75) × (196 N + 882 N) ≈ 0.25 × 1078 N ≈ 269.5 N

    Now, let's convert the horizontal force to kilograms:

    Force on the wall in kilograms:

    Force (in kg) = Horizontal Force (in N) / Acceleration due to gravity Force (in kg) = 269.5 N / 9.8 m/s² ≈ 27.5 kg

    So, the horizontal force exerted on the wall by the ladder with the person standing on it is approximately 27.5 kilograms.

    No idea if that's right, but it seems plausible. A fair bit of pressure over a small surface area.



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    #38
    GreeBo
    Registered Users Posts: 27,161 ✭✭✭✭GreeBo


    and just to allay any fears that AI will take over the world :)


    The weight exerted on the wall is the vertical component of the force due to the ladder and the person. This force is equal to the sum of the weight of the ladder and the weight of the person, both multiplied by their respective proportions along the ladder.

    Given:

    Person's weight (W_person) = 90 kg

    Ladder's weight (W_ladder) = 20 kg

    Ladder length (L) = 5 m

    Distance up the ladder (d) = 75% of ladder length = 0.75 * 5 m = 3.75 m

    Calculate the vertical component of the ladder's weight on the wall (F_ladder_wall):

    F_ladder_wall = (W_ladder * g) * (d / L)

    F_ladder_wall = (20 kg * 9.81 m/s²) * (3.75 m / 5 m) ≈ 147.15 N

    Calculate the vertical component of the person's weight on the wall (F_person_wall):

    F_person_wall = (W_person * g) * (d / L)

    F_person_wall = (90 kg * 9.81 m/s²) * (3.75 m / 5 m) ≈ 661.95 N

    Calculate the total weight exerted on the wall (Total_weight_wall):

    Total_weight_wall = F_ladder_wall + F_person_wall

    Total_weight_wall ≈ 147.15 N + 661.95 N ≈ 809.1 N

    Convert the total weight exerted on the wall from Newtons to kilograms:

    Weight in kg = Weight in N / g

    Weight in kg = 809.1 N / 9.81 m/s² ≈ 82.36 kg

    Therefore, the weight exerted on the wall is approximately 82.36 kilograms.



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    #39
    Lumen
    Registered Users Posts: 31,062 ✭✭✭✭Lumen


    https://www.boards.ie/discussion/comment/120937911#Comment_120937911

    Horizontal component, surely?



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    #40
    GreeBo
    Registered Users Posts: 27,161 ✭✭✭✭GreeBo


    https://www.boards.ie/discussion/comment/120938491#Comment_120938491

    That quote is what chatGPT gave me for the same question :)



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    #41
    Pique
    Registered Users Posts: 3,049 ✭✭✭Pique


    Yeah I had to modify the q slightly. You have to be ultra specific so it took a couple of tries to get it to answer the question.



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    #42
    PaybackPayroll
    Registered Users Posts: 131 ✭✭PaybackPayroll


    82.36+27.5 = 110

    110 = 90 (person) + 20 (ladder)

    So the first ChatGPT is the force on the wall (27.5) and the second answer is force on the ground (82.36)

    Isn't ChatGPT amazing? I think it's incredible.



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    #43
    Lumen
    Registered Users Posts: 31,062 ✭✭✭✭Lumen


    Not as amazing as hesker though.



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    #44
    GreeBo
    Registered Users Posts: 27,161 ✭✭✭✭GreeBo


    https://www.boards.ie/discussion/comment/120939700#Comment_120939700

    the problem is that it tells you both are the correct answer to the same question!



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    #45
    DublinDilbert
    Registered Users Posts: 5,374 ✭✭✭DublinDilbert


    https://www.boards.ie/discussion/comment/120921191#Comment_120921191

    These stand offs are well worth the money, have used mine both internally and externally. They also leave room to work and put a paint tray etc.


    ive used it internally as I always fear the ladder breaking the plaster board. So I just fix some timber across it to spread the load further again.



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