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Homework Help: Prove in case of projectile d^2 (v^2 ) / dt^2 = 2g^2

  1. Aug 2, 2015 #1
    1. The problem statement, all variables and given/known data
    for a projectile show that d^2 (v^2) / dt^2 = 2g^2

    2. The attempt at a solution
    =d/dt (d(v^2)/dt)
    =d/dt (2v)
  2. jcsd
  3. Aug 2, 2015 #2


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    Your attempt is using a very strange notation. Please write out the details using standard notation and explain what you are doing in each step.
  4. Aug 2, 2015 #3


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    Welcome to PF!
    The velocity v depends on t. You need to apply the Chain Rule to get the time derivative of v2.
  5. Aug 2, 2015 #4
    i have used second derivative on it
  6. Aug 2, 2015 #5
    In standard notation it is
  7. Aug 2, 2015 #6


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    That was not what was being questioned. The derivative of [itex]v^2[/itex], with respect to t, is NOT "2v". It is [itex]2v\frac{dv}{dt}[/itex].
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