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Help? Physics project

  1. Sep 29, 2011 #1
    This is a description of my requirements. I'm thinking about a trebuchet or a spring loaded device, possibly even a pneumatic one. However I have to use the given 5lb weight, any ideas on how? And also I'm a little confused on the "energy transfers".

    Help anyone? Thank you!

    1. Each team will get 3 shots at the target, with the total score being calculated
    from the best 2.
    2. At least two energy transfers must be used. Dropping the weight onto a level
    would be one transfer. Using energy of the falling weight to load a second
    mechanism would be a second energy transfer and would receive a multiplier
    of 2. Using that energy to load a third mechanism would get a multiplier of 3,
    and so on.
    3. Each method of energy transfer must be unique to qualify for a scoring
    multiplier. (In other words, a repeating method would count as 1 transfer, no
    matter how many times it occurs.)
    4. Bonus points will be applied to the summed score prior to any applicable
    multiplier.
    5. If the launcher cannot be designed to hit the target at 30 feet, a penalty will be
    applied for moving closer to the target using the following guide:
     
  2. jcsd
  3. Sep 29, 2011 #2

    gneill

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    Staff: Mentor

    What's the projectile? 30 feet is a fair distance for a light projectile, and you're not going to have much energy to spare to launch a heavy one; Every transformation of energy will exact a toll, as such conversions are never 100% efficient. What are the limitations on the size of your build?
     
  4. Sep 29, 2011 #3
    Here are the requirements. For the projectile I was thinking maybe a tennis or some kind of rubber ball.

    The Projectile
    1. The projectile will be made of any available foam-like material with the largest
    dimension of the projectile no more than 5 inches and the smallest dimension
    of the projectile no less than 0.5 inch.
    2. Consider a foam-like material any material that can be compressed and when
    relaxed, returns to its natural position. (Toy ball, pool float, sponge, etc.)
    3. The project guru must approve the material chosen.
    The Launcher
    1. The launcher may be constructed with any available materials, but must fit
    inside an imaginary 4-foot cube (including any motion of the launcher).
    2. The distance to the target will be measured from the front edge of the cube.
    3. The launcher must be placed on the floor for operation.
    4. The provided weight may be attached using any chosen method within the
    cube.
    5. The only human intervention allowed is the loading and release of the weight.
    6. The launcher must involve at least two methods of energy transfer;
    specifically, simply dropping the weight on one end of a lever to launch the
    projectile would not be acceptable (i.e. a simple catapult is not acceptable).
     
  5. Sep 29, 2011 #4

    gneill

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    Staff: Mentor

    The rules don't seem to be clear on whether or not the energy transfers have to be productive and contributing directly to the projectile's motion... In other words, suppose most of the brick's energy were used to stretch an elastic band that will eventually fire the projectile, but some of the energy were used to make a series of excursions through rotational, pneumatic, spring compression, etc., before finally pulling the trigger on the elastic. Would that count?
     
  6. Sep 29, 2011 #5
    Um, I am not sure. Can you explain more about the excursions?
    I'm kind of new at this, I've never taken a physics course before... :/
    I know, sad. My high school never offered it, at least not with a decent teacher.
     
  7. Sep 29, 2011 #6

    gneill

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    Staff: Mentor

    By "excursions" I mean that the impetus to pull the trigger on the firing mechanism is channeled through several mechanisms that store and release energy in different ways. Try to think of different ways of storing or moving mechanical energy around.
     
  8. Sep 30, 2011 #7
    Yes, the energy transfers do not have to contribute directly to the motion of the projectile. So the example you listed above WOULD work.
     
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