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What would be the force in pounds of 25,000 lbs. moving at 40fps

  1. Aug 21, 2011 #1
    what would be the force in pounds of 25,000 lbs. moving at 40fps

    I realize this is probably a very simple question for most of the people on this forum but it is above my very basic education and memory of 40 years ago. Can anyone answer it?
  2. jcsd
  3. Aug 21, 2011 #2


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    No because the question doesn't have enough information. A force is an applied phenomenon. This object must actually hit something before a force can exist. And it depends on what kind of object it hits. If you hit something rock hard like a brick wall, you will experience huge forces upon contact. If it hits a massive pile of soft foam, the force will be much smaller.
  4. Aug 21, 2011 #3
    solid concrete
  5. Aug 21, 2011 #4


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    and you need to know what the object is that is being shot at the concrete. This is actually a completely experimental problem, there is no theoretical calculation that can answer your question. I believe someone mentioned around here that typical car->solid object collisions typically have forces of 5,000N-10,000N upon impact but don't quote me on that. Your object is a bit heavy for a car but it is traveling at a slower speed so maybe the 10,000N range maybe realistic, I don't know.
  6. Aug 21, 2011 #5
    solid concrete running into solid concrete, I just need a general guess in pounds. I will not quote you on it, I just need a very wide ballpark figure.
  7. Aug 21, 2011 #6
    Would it be more than 25,000lbs. but less than a bizzillion? Could you narrow it down for me just a little?
  8. Aug 21, 2011 #7
    You can get an extremely rough estimate by guessing at the time of contact, and using Force = mass * acceleration (in this case, deceleration). For concrete blocks, this could be around 0.1 seconds.
  9. Aug 21, 2011 #8
    and what would be the answer to that
  10. Aug 21, 2011 #9


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    One can determine momentum, m*v and kinetic energy 1/2mv2. If there is not change in velocity, i.e., acceleration, then there is no net force.

    There could be friction with air or surface on which something is traveling, in which case, one needs drag and/or friction coefficients, and some idea of the area projected into the air, and/or weight.

    If the mass collides with something, one can determine an impluse. mΔv = FavgΔt = Impulse


  11. Aug 21, 2011 #10
  12. Aug 21, 2011 #11
    What would be the force in pounds? Not the formula to figure it out! I need the answer to the question, not a math lesson.
  13. Aug 21, 2011 #12
    Look, I'm not trying to be a jerk, but you are being extremely lazy. You could have typed the conversion into google in the time it took you to ask me about it.

    We aren't a personal answer service. This forum focuses on learning.

  14. Aug 21, 2011 #13


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    around 250,000 pounds would be my very rough guess...you'd have to have more data for a better figure.
  15. Aug 21, 2011 #14


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    He's not being lazy. Using the internet to get answers - even simple conversions - is a skill, learned through exposure. You know to do this but not everyone does. PF attracts a very wide array of people. PF may not be geared to helping people who have little experience - but that's not his failing.
  16. Aug 21, 2011 #15
    Thank you for that answer. Sorry, I am not a math student and don't have time to learn about it at this point in my life. I just needed the answer to the question. When I registered there was nothing mentioned about qualifications. Be careful not to judge others, I am ignorant but I am far from lazy. Thanks again.
  17. Aug 21, 2011 #16
    I'd guess that the force would peak between 1 million - 20 million pounds, with a time duration of a few milliseconds. This is based on a few years of experience with this sort of thing, and that's the best I can do without 1) more information and 2) spending hours on the problem.
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