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Researching plots

  1. Apr 18, 2010 #1
    Hey im a new guy here...and im trying to do research for a story of mine...i am trying to figure out the radius of a 396 foot tall wall, (flat on the inside) in the shape of a circle that can hold approx. 100 000 people...and in order to do that...i need to figure out the approximate mass of a human being, having rough measurements of 6 x .5 x 2 feet...can anyone help me figure it out?

    im a bit stumped on it...i already know how to figure out the diameter from the total mass/ volume...in just trying to figure out the total volume based upon the standard human mass, multiplied by the height of teh wall and by 100 000 (people)
    Last edited: Apr 18, 2010
  2. jcsd
  3. Apr 18, 2010 #2
    First you calculate the total volume of the bodies (assuming 6ft x .5ft x 2ft), which is 6ft^3 per person. 600,000ft^3 total.

    We know this is the total volume for the bodies, thus the total volume of the silo.

    We know that the volume of a cylinder is equal to the radius squared times the height times pi.


    We know V, pi, and h. Just solve for r.

    600,000ft^3 = pi * r^2 * 396ft

    r^2 = 482.3ft^2

    r ~ 22ft.

    A 22 ft radius.
  4. Apr 18, 2010 #3
    a 22 ft raduis to fit in 100 000 people with the approximate mass of 6 feet cubed...?

    I find this to be a little bit...problematic... :frown:
  5. Apr 18, 2010 #4
    Please note that mass and volume are completely different physical quantities. Also, there is the question of packing human beings. I don't understand what you mean by a circular wall that is flat on the inside. Please provide a diagram.
  6. Apr 18, 2010 #5
    What's problematic about that? This means that the silo is 44ft wide and almost 400ft high. I think that's a reasonable size.

    Well... I assumed that these bodies are going to be stacked and densely as possible. Are these dead bodies in this silo or did you want to know the size if people were only standing on the ground? If so, then the height of the people would be irrelevant.
  7. Apr 18, 2010 #6
    okay..i was trying to specify...but it seems i failed to do that...i cant provide a diagram at the moment...but the people...would be standing...and to fit 100 000 people from where they are standing...not piled up on each other...

    in their view...they are surrounded by a wall thats 396 feet high... no piling of any sorts. if they were all standing, side by side...shoulder to shoulder...(from the head...2 feet apart in all directions)...so i guess to multiply their height to the height of the wall would be the proper thing to do as well then...ack~

    i'm really trying hard to describe what it is im trying to figure out...but my words are noo good at all...ill try to create a diagram to better explain what it is im trying to figure out...
  8. Apr 18, 2010 #7
    So what I'm envisioning is a large circular wall. People standing, filling in this circle so that the center of their bodies are 2 ft away in each direction. This would mean that their shoulders are touching, and there is about 1 ft between each line of people.

    We can do this by saying that the total area each person takes up is 2ft * 2ft = 4 sq ft.

    Now, because the people are standing, the height of the people and the height of the wall is irrelevant.

    A = 4 sqft * 100,000 people
    A = 400,000 sq ft

    A = pi * r^2
    400,000 sq ft = pi * r^2

    r = 357ft

    So the wall would have a radius of 357 ft, or a diameter of twice that, 714 ft.
  9. Apr 18, 2010 #8
    ahhhh...thank you...i was in the middle of making a diagram...because i thought i wasnt being clear enough (im not very good with communicating my thoughts aloud...)
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