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Homework Help: Need help with some kinematics/vectors

  1. Sep 12, 2008 #1
    1. The problem statement, all variables and given/known data
    During World War 1, the Germans had a gun called Big Bertha that was used to shell Paris. The shell had an initial speed of 2.26 km/s at an initial inclination of 65.8 degrees to the horizontal. The acceleration of gravity is 9.8 m/s^2. How far away did the shell hit? Answer in units of km.
    How long was it in the air? Answer in units of s.

    2. Relevant equations
    Vf= Vi + a (tf-ti)
    y= yi + vit + 1/2 at^2.

    3. The attempt at a solution
    I did it several different ways and keep getting answers that are wrong. I got 4.10 s for time, then I got .420s and .840 s. I keep getting the wrong answer. Once I figure out how to do time, I'll be able to do the distance part. Keep in mind the a is in meters per second but kilometers is required in the answer.
  2. jcsd
  3. Sep 12, 2008 #2
    Which of the two eqns did you use to find the time of flight t? What values did substitute?
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