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: Finding muzzle velocity using range and height of barrel

  1. Jun 13, 2010 #1
    1. The problem statement, all variables and given/known data
    Ok, so pretty much, I built an air cannon for my physics assignment. I need to determine the muzzle velocity. I know the angle of the barrel, the height of the muzzle about the ground and the distance the projectile covered. I fired projectile at multiple pressures in order to determine the effect of pressure of muzzle velocity. I am ignoring drag and friction for these equations.

    2. Relevant equations
    Let v0 = Initial muzzle velocity
    o = angle of barrel = (33.82 Degrees if this is neccessarY)
    Height of barrel = h = 1.13m

    3. The attempt at a solution
    Total time of flight= t = v0sin(o)/9.8^2+ (v0sin(o)^2/9.8^2 - 2*h/9.8)^0.5
    Distance travelled = v0cos(o) * t
    = v0cos(o) * (v0sin(o)/9.8^2+ (v0sin(o)^2/9.8^2 - 2*h/9.8)^0.5)
    I need the rearrange this equation so v0 is the subject so I can implement this in an excel spreadsheet as I have literally hundreds of these to determine.
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. Jun 14, 2010 #2

    Andrew Mason

    User Avatar
    Science Advisor
    Homework Helper

    What is your question?

    If you are trying to find muzzle velocity, you have to solve these equations for time:

    (1) [tex]x = v_0\cos\theta t[/tex]

    (2) [tex]y = v_0\sin\theta t - \frac{1}{2}gt^2[/tex]

    Find the muzzle velocity by substituting t into (1).

    AM
     
    Last edited: Jun 14, 2010
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook