Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Cannon fired on slope

  1. Feb 17, 2006 #1
    Hello all,

    I've searched and browsed and I haven't found anyone else that's asked this question, so I will ask it here.

    A cannon point at a fixed angle of 30° is placed on a slope of 12° and fired uphill at an initial velocity of 30 m/s. What is its range?

    I thought about making the x direction going up the hill, and I also tried it with a normal coordinate system. Any help is greatly appreciated.

  2. jcsd
  3. Feb 17, 2006 #2
    launching a projectile on a slope of 12 degrees at an angle of 30 degrees, is the same as launching it at 42 degrees. Therefore, you can use the projectile equations as usual, just using an angle of 42 degrees instead, then simply work out the point of intersection between the cartesian equation generated, and the line y = (tan12)x. Then use a little trig to work out the distance from the origin and the point of intersection.
    Last edited by a moderator: Feb 17, 2006
  4. Feb 17, 2006 #3
    http://photo-origin.tickle.com/image/69/3/7/O/69370364O624412945.jpg [Broken]
    Last edited by a moderator: May 2, 2017
  5. Feb 17, 2006 #4
    i see.. thank you so much!
  6. Feb 17, 2006 #5


    User Avatar
    Science Advisor
    Homework Helper

    I would make one comment. finchie_88 overlooked one key word (which I highlighted in your original post). Your angle is the difference between 30 and 12, not the sum of 30 and 12.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook