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Homework Help: Instantaneous velocity and friction

  1. Mar 21, 2004 #1
    We need to know the instentaneous velocity formula for a car launched down a hallway. we also need to figure out how to calculate all the friction involved in this. please help.
  2. jcsd
  3. Mar 21, 2004 #2
    The car's velocity at a certain moment [tex]t[/tex] is:
    [tex]\vec V(t) = \vec V_0 + \vec at[/tex]
    The car's acceleration is defined as:
    [tex]\vec a = \frac{\vec \Sigma F}{m}[/tex]
    In this case the only force on the motion axis (X) is the friction:
    [tex]\vec a = \frac{\vec f_k}{m} = \frac{-N\mu }{m} = \frac{-mg\mu }{m} = g\mu[/tex]

    Therefore the car's velocity is:
    [tex]\vec V(t) = \vec V_0 - g\mu t[/tex]

    Does this answer your question?
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