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Homework Help: Trajectory and Force Problem: shot putter launch

  1. Oct 30, 2009 #1
    1. The problem statement, all variables and given/known data

    A shot putter launches a 7.22 kg shot by pushing it along a straight line of length 1.84 m and at an angle of 33.0° from the horizontal, accelerating the shot to the launch speed from its initial speed of 2.3 m/s (which is due to the athlete's preliminary motion). The shot leaves the hand at a height of 2.30 m and at an angle of 33.0°, and it lands at a horizontal distance of 15.7 m.What is the magnitude of the athlete's average force on the shot during the acceleration phase? Treat the motion during the acceleration phase as though it were along a ramp at the given angle.

    2. Relevant equations

    y=v0sin[tex]\vartheta[/tex]0t - (1/2)gt2
    The trajectory and range equations can be derived from these two.
    I'm guessing I'm going to have to use F=ma too if mass, acceleration, force are involved.

    3. The attempt at a solution

    I'm having a hard time turning the situation into a picture that makes sense to me of the motion that's happening. I'm not sure what to do with v initial... unless maybe I'm actually supposed to use it to find acceleration based on how far it's traveled using v2-v02=2a(x-x0). Maybe I don't even have to use the trajectory equations at all? Because once I find a, I have m, so all I have to do is solve for F. Except, I'm still not sure how to get a... why do I need the angle? Do I have to resolve something into components?

    Argh... I don't think I'm setting up the situation properly in my mind...
  2. jcsd
  3. Oct 30, 2009 #2
    Try drawing out the problem on a piece of paper and lablel all given information. It will help you a lot. :) Post your attempt here and if your still struggling I'll help you out. As well you will need the impulse equation, which is the change in momentum. This will allow you to find the answer you are looking for and might clarify the picture for you a bit :)
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