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Instantaneous velocity of a object in projectile motion

  1. Nov 13, 2010 #1
    1. The problem statement, all variables and given/known data
    stone is thrown horizontally with a initial speed of 8.0 m/s (Vxi)
    Air resistance is negligible. average acceleration due to gravity = 9.8 N/Kg (down) [ay]

    2. Relevant equations
    dx= Vxi/ time
    Vfy= vyi + ay x time
    Instantaneou velocity equation? :S



    3. The attempt at a solution
    okay so it tells me to find horizontal and vertical components of displacement and instantaneous velocity at time=0.0s/1.0s/2.0s and 3.0s isn't Vyi given (initial y velocity SINCE it's 0?) and (vxi is also give - 8.0 m/s)
    BUt how do i find INSTANTANEOUS velocity?
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. Nov 14, 2010 #2

    tiny-tim

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    Welcome to PF!

    Hi NightRunnerz! Welcome to PF! :smile:
    Instantaneous velocity just means the velocity at that particular moment (ie, the word "instantaneous" is unnecessary :rolleyes:)

    (and if you need the speed, use Pythagoras! :wink:)
     
  4. Nov 14, 2010 #3
    OKAY so by velocity you mean V as in speed right?
    dotdotdot m/s2?
    .....m/s2?
     
  5. Nov 15, 2010 #4

    tiny-tim

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    Hi NightRunnerz! :smile:

    (just got up :zzz: …)
    No, speed and velocity are different.

    Speed is the magnitude of velocity.

    Velocity has components, speed doesn't.

    The question tells you to find the horizontal and vertical components of instantaneous velocity … that's vx and vy.
    m/s2 is acceleration :confused:
     
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