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Will my physics experiment work?

  1. Dec 5, 2009 #1
    For homework, I'm supposed to design an experiment and work it out using estimated values. I didn't really have an idea till I got to my swim practice later on. I heard my coach saying that you should try to dive off of the blocks at a 45 degree angle in order to maximize your distance. I thought about it at first, and thought that the angle should be slightly less because the height of the start and end points are not the same (the block is roughly 28 inches above pool level). In addition, would different angles result in different entrance speeds?

    I thought about this and came up with the conclusion that although the entrance speeds may be the same, the horizontal and vertical speeds are different. In order to maximize the horizontal entrance speed, would you have to push off the block at basically a horizontal path? But then, if you angle your dive upwards you are able to let gravity add to your momentum and therefore add to your speed.

    Will this project work out? Or will I find out that no matter what angle you dive at it doesnt matter (or is simply a straight line)?

    Can anyone help me get stared on the right track? For my experiment, I'll be using myself as the model. Because I don't have access to a pool this moment, and don't know of a better way to measure the force of which i push off the block, I think I should somehow calculate the force with which I jump and use that value instead. How would I go about doing that?
  2. jcsd
  3. Dec 5, 2009 #2


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    Homework Helper

    using projectile motion, you can find the maximum angle for the maximum range. But how to measure your initial velocity may become a bit difficult.
  4. Dec 5, 2009 #3
    do I need my initial velocity? or will initial force from my jump work?
  5. Dec 5, 2009 #4
    I sort of have a general idea of what I want to do, but I just don't want to do it all and have it come to the conclusion that it doesnt matter or something like that.

    Anyways, this is my plan

    -Find force of my jump (not sure how to go about doing this)
    -Split force into vectors
    -Find distance away from block I will land
    -calculate the velocity at which I will enter
  6. Dec 6, 2009 #5


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    The force of your jump will allow you to calculate your initial velocity once you are airborne. It is that initial velocity that you will need to calculate the projectile trajectory.
  7. Dec 6, 2009 #6
    Well one thought is just to see how high you can jump vertically from roughly the same posture in terms of leg flex (try to maintain the angle at the waist so that the center of mass remains stationary--somewhere between your naval and sternal notch). It would be best if you have access to a video camera but even w/o you should be able to get a rough idea. The other way to do it would be to measure the hang time which could be gotten pretty accurately from a vid recorder if you can advance frame by frame.

    I'll leave the math to you but holler if you need help.
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