Vf (final velocity)

Discussion in 'Physics' started by ronn, Feb 13, 2009.

  1. ronn

    Thread Starter Member

    Nov 1, 2007
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    0
    if i'm conducting an experiment (like letting a small toy car run from start, time it from start to the certain point that i want to know Vf(final velocity))
    what formula should i use to know Vf? should i know the accelration first but how? i'm trying to use the formula
    a = (Vo + Vf)/t where
    a=acceleration
    Vo=Inital velocity in (meters/s)
    Vf=Final velocity in meters per second
    t=time in seconds
    not constant acceleration
    but still a liitle bit confused of what to do
    thanks
    (sorry for my wrong formula of acceleration before)
    Ron
     
    Last edited: Feb 14, 2009
  2. mik3

    Senior Member

    Feb 4, 2008
    4,846
    63
    Will the car have a constant acceleration?

    How you will measure it?
     
  3. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
    5,692
    901
    Your first equation for acceleration (i.e., a = (Vo + Vf)/2 ) just doesn't make sense. Why don't you write the units for velocity and see whether you end up with the correct units for acceleration doing it that way?

    John
     
  4. mik3

    Senior Member

    Feb 4, 2008
    4,846
    63
    If the car has a constant acceleration then you can use:

    s=0.5*a*(t^2)

    to find the distance

    Otherwise you need to make a circuit which will measure the speed of the car at any instant in time and integrate it as to find the distance (s).
     
  5. fanta_hanu

    New Member

    Mar 9, 2009
    8
    0
    (Vf)2-(Vi)2 = 2*a*S

    Where Vf = Final Velocity
    Vi=Initial Velocity(=0,if it starts from rest)
    a= acceleration
    S= distance covered.

    S=[(Vi)*t]+[.5*a*t2]

    Where t= time of journey..

    Using these you can calculate the required parameters...provided,the acceleration in uniform..

    If its not uniform and a variable one,Use differential form..

    a=dv/dt=d/dt(v) where v=velocity,in terms of time

    Hope this would solve your problem...If you want more,do let me know...

    Cheers,
    hanu
     
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