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Find the instantanous velocity

  1. Apr 8, 2009 #1
    1. The problem statement, all variables and given/known data

    Find the instantaneous velocity at t=1 by computing v(1)= [h(1+LaTeX Code: \\Delta t)-h(1)]/LaTeX Code: \\Delta t

    I found that v(1)= -8ft/sec. Also I know h(1)=24 but i dont understand how to manipulate the h(1+LaTeX Code: \\Delta t) to get the solution.


    2. Relevant equations

    h(t)=16+24t-16t2


    3. The attempt at a solution

    The solution the teacher gave is v(1)=-8-16tLaTeX Code: \\Delta
     
  2. jcsd
  3. Apr 8, 2009 #2

    Cyosis

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    Homework Helper

    Write out [tex] \frac{h(1+\Delta t)-h(1)}{\Delta t}[/tex]. The part you have a problem with is probably the [itex] h(1+\Delta t)[/itex] term I will give you a hint. [itex] h(1+\Delta t)=16+24(1+\Delta t)+... [/itex] fill in the rest and work out the brackets.

    Note that for an instant of time [itex]\Delta t \rightarrow 0[/itex] so your final answer is correct.
     
    Last edited: Apr 8, 2009
  4. Apr 8, 2009 #3
    How did you get that h(1+t)=16+24(1+t)?

    and when i fill in the rest i get 16+24(1+t)-24 which when worked out would be 16+24t and is not right

    :confused:
     
  5. Apr 8, 2009 #4

    Cyosis

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    Don't overlook the dots. [itex]h(1+\Delta t)=16+24(1+\Delta t)+... [/itex] my intention was for you to fill in the dots, so basically add the quadratic term to it as well. I hope this is sufficiently clear if not just ask again!

    Edit: I just noticed that the same question was asked in the correct introductory physics section. Perhaps a mod could merge this thread with https://www.physicsforums.com/showthread.php?t=305889.
     
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