Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Pain/Damage - If I dropped an ant

  1. Jan 14, 2007 #1
    Say we had a six foot wall, I jumped off and measured the pain/damage recieved because of the fall, how would that differ to an ant if it was dropped from the same height? Because of it's size/weight difference...
     
  2. jcsd
  3. Jan 14, 2007 #2

    Gokul43201

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    How is this question answered by Relativity? I hope you're not using the layman connotation of that term. Forget what Einstein said; Relativity is not about how it feels when you're sitting on a hot stove.
     
    Last edited: Jan 14, 2007
  4. Jan 14, 2007 #3

    Hootenanny

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Could we tone down the language please Complex? Otherwise your thread is liable to be locked. Gokul was just enquiring why you though relativity should be able to answer you question as opposed to classical physics. I don't think this question is answerable anyway, since pain is subjective; how do you intend to measure the pain experienced by an ant?
     
  5. Jan 14, 2007 #4
    I didn't ask for his ignorance; simply telling me where it should be would be more helpful than anything...

    That's why I put pain/damage... I'm just interested to find out how free fall effects different sized life forms when it hits a surface...

    Would it's difference in size/weight effect how damaging the fall would be to it compared to us?
     
    Last edited: Jan 14, 2007
  6. Jan 14, 2007 #5

    Gokul43201

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Take it easy with the personal attacks. How am I to know that you didn't have some non-obvious reason for posting this under Relativity? Which is why I asked you.
     
  7. Jan 14, 2007 #6

    DaveC426913

    User Avatar
    Gold Member

    1] An 2mm ant's surface-to-weight ratio is on the order of a million times greater than a human's (1000^2). This means that when ants fall, they reach terminal velocity quickly, and literally float down.
    2] An object's ability to withstand crushing is based on its cross-sectional structures (i.e. legs). An ant's cross-sectional area-to-weight ratio is also about a million times greater than a human's. This means it can withstand more weight (proportionally) before collapsing.

    Likewise, an elephant's area-to-weight ratio is a few orders of magnitude smaller than a human's. An elephant cannot jump, and if it tried, it would break its legs.

    Why? The square-cube law.

    Let's leave the elephant alone and instread create a giant that is exactly human-shaped, only 12 feet tall.

    Code (Text):

    Critter  Height (1D)  leg diam.    X-sectional area of leg (2D)   weight (3D)
    Human     6'              5"                5^2 = 25"               200 lbs.
    [U]Giant    12'             10"               10^2 = 100"             1600 lbs[/U]
             2x               2x                    4x                    8x
     
    Notet that the legs of the giant are four times as thick in cross-section but they have to support eight times as much weight. They are near the breaking point. A fall from one foot might break a giant's legs.
     
    Last edited: Jan 14, 2007
  8. Jan 14, 2007 #7
    the bigger they are the harder they fall holds true then eh?
     
  9. Jan 14, 2007 #8

    quasar987

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    "I like big fat men like you. When they fall, they make more noise. And sometimes they never get up."

    Tuco was right!
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?