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Projectile Motion Bullet Shot Help

  1. Nov 25, 2013 #1
    1. The problem statement, all variables and given/known data


    bullet shot horizontally over level ground with a velocity of 300m/s. at the instant that the bullet leaves the barrel, its empty shell casing falls vertically and strikes the ground with a vertical velocity of 5.00m/s

    how far does the bullet travel

    what is the vertical component of the bullet's velocity at the instant before it his the ground?



    I tried a bunch of stuff and I didnt get the right answer, can someone just point me in the right direction? Please, at least tell me which equation to use cause I cant figure this out.
     
    Last edited: Nov 25, 2013
  2. jcsd
  3. Nov 25, 2013 #2

    NascentOxygen

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    Staff: Mentor

    Hi yogoes123. Is there a question attached to this statement?
     
  4. Nov 25, 2013 #3
    sorry i somehow missed that, very sorry i edited it.
     
  5. Nov 25, 2013 #4

    NascentOxygen

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    Same here. I can't figure out which equation to use until I have condensed that wordy statement into something that looks more mathematical.

    First thing, write down all the information that you know, expressing it as values of variables, e.g.,

    bullet: vi = 300 m/sec

    casing: vi = ???
        vf = ???

    etc.
     
  6. Nov 26, 2013 #5

    rude man

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    what is distance d of fall given time of fall T?
    what is velocity of fall, given time of fall T?
     
  7. Nov 26, 2013 #6
    Ok guys i think there is a bit of confusion. The question says the bullet has a horizontal velocity of 300 m/s.

    They want you to find range.

    They also say the bullet shell falls vertically at a rate of 5 m/s, not sure why but its probably needed.

    Thats all they give u.

    Horizontal Velocity of bullet: 300 m/s

    Vertical velocity of SHELL: 5m/s
     
  8. Nov 26, 2013 #7

    rude man

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    You need to quote the actual problem verbatim for us. The casing will not fall with uniform velocity.
     
  9. Nov 26, 2013 #8
    A sharpshooter shoots a bullet horizontally over level ground with a velocity of 3.00 x 10^2 m/s. At the instant that the bullet leaves the barrel, its empty shell casing falls vertically and strikes the ground with a vertical velocity of 5.00 m/s

    a) How far does the bullet travel

    b) What is the vertical component of the bullet's velocity at the instant before it hits the ground.
     
  10. Nov 26, 2013 #9
    Break this down into your knowns and unknowns.

    You only have four kinematic equations.

    U1L6a1.gif

    This problem is a projectile problem that is asking you to break things up in terms of x and y. First the shell moves initially with the bullet at 300 m/s horizontally, and then when it approaches 0 m/s, due to gravity it accelerates vertically at 9.8 m/s2 towards the earth to reach a final velocity of 5 m/s.

    So what do you know?

    Horizontal Movement

    Vix= 300 m/s
    t=(5m/s)/(9.8m/s2)=0.5097s
    ax= 0 m/s2
    Δx=?

    Δx=(vix)(t) + (0.5)(ax)(t)2

    Vertical Movement

    viy= 0 m/s
    vfy= 5m/s
    ay= 9.8 m/s2
    Δx=?

    vfy2 = viy2 + (2)(ay)(Δy)
     
    Last edited: Nov 26, 2013
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