1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
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: Projectile motion gun help

  1. Feb 9, 2012 #1
    1. The problem statement, all variables and given/known data

    7. During World War I, the German army bombarded Paris
    with a huge gun referred to, by the Allied Forces, as “Big
    Bertha.” Assume that Big Bertha fired shells with an initial
    velocity of 1.1 x 10^3 m/s [45° above the horizontal].

    (a) How long was each shell airborne, if the launch point was the same as the landing point

    2. Relevant equations

    dy = v1xT+1/2ax X t^2

    3. The attempt at a solution

    v1 = 1.1 x 10^3
    a= -9.81
    t = ?
  2. jcsd
  3. Feb 9, 2012 #2
    I assume "by the same point as the landing point" means the same y coordinate. If the point was the same the gun would be firing straight up.

    Anyway, since the gun is at a 45 degree angle, you can find the y component of the initial velocity, and you know the acceleration of gravity. Just use the equation x = x0 + v0t + .5at^2 to solve for t.
  4. Feb 9, 2012 #3
    What would x equal

    t = Squared root x-.5(-9.81)

    thanks in advance
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook