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Homework Help: Maximum Range

  1. Feb 12, 2010 #1
    1. The problem statement, all variables and given/known data

    On level ground, what is the maximum range (in m) of a cannon with muzzle speed 322 m/s?

    Please take a look at this:


    2. Relevant equations

    R = (V0^2 * sin2angles)/g

    3. The attempt at a solution

    I think (not sure) the angles in the pic is 30 degree. And came up with the answer:

    R= 9162.55 m, and it is wrong. Please help with direction as well as formula and the final answer.

    Thanks so much!
  2. jcsd
  3. Feb 12, 2010 #2

    Gib Z

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    Homework Helper

    Umm...unless you were meant to get a protractor and measure the angle, you don't have enough information for the problem. Also, the "direction" of the range is to the right. Were you given ANY other information?
  4. Feb 12, 2010 #3
    If an object is launched on a flat surface the maximum range comes when the angle is 45.
  5. Feb 12, 2010 #4
    Take another look at your range formula, you're given velocity and you know it's proportional to the sine of 2*angle. For what angle is sine 2*angle a maximum?
  6. Feb 12, 2010 #5
    Please click on the link given. That's all I got!!!


  7. Feb 12, 2010 #6
    So you mean after looking at the pic link, and you think the angle is 45 degree????
  8. Feb 12, 2010 #7
    Does it look like the picture is drawn to scale?
  9. Feb 12, 2010 #8
    In all fairness, even if it was scaled up the angle would remain identical, similar triangles and such. But, I don't think they're putting emphasis on the picture here, the question is simply "What is the maximum range for a cannon with muzzle velocity 322m/s?". So Jebus_Chris is right.
  10. Feb 13, 2010 #9
    So, how to resolve this problem? Please help!!!
  11. Feb 13, 2010 #10
    If an object is launched on a flat surface the maximum range comes when the angle is 45.
  12. Feb 13, 2010 #11
    So It comes out with:

    R = (V0^2 * sin2angles)/g

    => R = 10580 m. Is this correct?
  13. Feb 13, 2010 #12
    I got it right. Thanks so much for your help ;) Please help me to complete the "Calculate the time it took the marble to travel from N to P" problem ;)
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