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To find time

  1. Jul 16, 2005 #1
    I want to know how to find the time it takes for a mass to reach a velocity if a force is applied to it.
    Last edited: Jul 16, 2005
  2. jcsd
  3. Jul 16, 2005 #2

    Doc Al

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    One way is to apply Newton's 2nd law to find the acceleration, then integrate--or apply kinematic equations--to find the time: [itex]v_f = v_i + a t[/itex].

    Another (equivalent) way is to use the "impulse-momentum" theorem: [itex]F \Delta t = m \Delta v[/itex].
  4. Jul 16, 2005 #3
    i'm terrible at math, can you isolate time on one side of the equation?
  5. Jul 17, 2005 #4


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    What equation are you using?
  6. Jul 17, 2005 #5
    Vf=Vi + at
  7. Jul 17, 2005 #6


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    Note that there is no mention of a constant force being applied here.

  8. Jul 17, 2005 #7
    [tex]t = \frac{v_f - v_i}{a}[/tex]

    Make note of what ZapperZ said, though.
  9. Jul 17, 2005 #8


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    cscott has done this for you, but you won't get very far with physics if you don't first brush up on elementary algebra. I strongly recommend you learn the math first.
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