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A plane drops a missile

  1. Oct 7, 2015 #1
    1. The problem statement, all variables and given/known data
    a plane, traveling at 200 m/s in the X direction, drops a missile which has a constant acceleration of 7 m/s^2 at an angle 10 degrees below horizontal. If the plane is 1250 m high when it fires, how far (in the x direction) from where it was fired will the missile come down?

    2. Relevant equations
    ?

    3. The attempt at a solution
    I have absolutely no idea how to start this problem... could I possibly break the 7m/s^2 into y and x components using cosine, sine and the angle of 350 (10 degrees below the horizontal)?
     
  2. jcsd
  3. Oct 7, 2015 #2

    Bystander

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    Sounds like a start.
     
  4. Oct 7, 2015 #3

    okay...well how can I possibly keep going after that?
     
  5. Oct 7, 2015 #4

    phinds

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    How about if you go that far and see if anything occurs to you.
     
  6. Oct 7, 2015 #5

    okay so I'm very much so struggling with this problem, but I tried to solve for the time when the missile will hit the ground

    Δy=Voy(t) + ½ ay(t)2 → -1250= 0 (t) +½ (-1.2155) (t)2→ t= 45.35 seconds

    is that correct so far?
     
  7. Oct 7, 2015 #6

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    Looks about right --- haven't got my calculator to check for dotting "i's" and crossing of "t's" as far as sin(10°), but definitely the correct ballpark and handling of the numbers. Please continue.
     
  8. Oct 7, 2015 #7

    after that, I plugged t into the equation Vfx= Vox +ax(t) → Vfx= 200+(6.894)(45.35) → and got 512.643 m/s for Vfx. I then multiplied the final velocity by the time (45.35 seconds) to get the Δx, which is 23248.3555 m . Is that correct?
     
  9. Oct 7, 2015 #8

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    That non-zero initial velocity tripped you up. How far does the missile travel if the initial velocity is zero? You did fine with the y-component.
     
  10. Oct 8, 2015 #9
    so should it just be (6.894)*(45.35) then? With that I get an initial of 312.643 and then multiplied by time I get 14178.3555 m
     
  11. Oct 8, 2015 #10

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    You used "d = (1/2)at2" for the y-component. I told you that was correct.
     
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