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Homework Help: Projectile Launched Question

  1. Sep 23, 2013 #1
    1. The problem statement, all variables and given/known data
    A 500kg object is launched from the top of a 12m building with intial speed of 5.2m/s and angle of 38degrees. How far away does object land?

    2. Relevant equations
    y=vit + 1/2at^2
    quadratic formula

    3. The attempt at a solution
    first i separate the initial velocity into its x and y coordinates. Using cos and sin. Next I input this found value of the y direction velocity into the y=vit + 1/2at^2. I rearrange this formula and solve it as a quadratic for time, and I use the positive time value which I got as 1.92s. Next I multiply this time value by the velocity in the x direction I got from doing the cos of the initial velocity.

    I end up getting the object lands 7.9 m away from the building. Can anyone check and see if this is right? Also the mass was negligble right?
  2. jcsd
  3. Sep 23, 2013 #2
    Your method is correct.

    If you want your numbers to be checked, post the intermediate values you got (init. velocity components, time of flight).
  4. Sep 23, 2013 #3
    Well the initial velocity was 5.2m/s. The y component of this is 3.2m/s, and the x component is 4.097 m/s.

    When I solve for time from the quadratic formula, I get -1.272s and 1.923s. I use the positive value cause you cant have negative time.

    Now I just multiply the time by the x component velocity and get 7.9m.
  5. Sep 23, 2013 #4
    Everything looks good.
  6. Sep 23, 2013 #5
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