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Homework Help: Physics help ?

  1. Jan 4, 2010 #1
    Physics help!!?

    1. The problem statement, all variables and given/known data
    A skydiver has mass of 75g, travelling at 80mph, drag force on skydiver is 650N. Find acceleration of skydiver at 80mph (g=10n/kg??)

    2. Relevant equations

    Do I use a=f/m
    3. The attempt at a solution
    No attempt - im really stuck!
  2. jcsd
  3. Jan 4, 2010 #2


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    Science Advisor
    Homework Helper

    Welcome to PF!

    Hi Neveda! Welcome to PF! :wink:

    (do you mean 75kg?)

    Yes, use Ftotal = ma.

    What is the total force on the skydiver? :smile:
  4. Jan 4, 2010 #3
    Re: Physics help!!?

    Yes, use a=F/m
    You need to find the resultant force on the diver.
    There are two forces acting on him in this question.
  5. Jan 4, 2010 #4
    Re: Physics help!!?

    EEk.. I think maybe it is 75kg and the total force is 650N But I have no idea how to even begin to work something like this out :(
  6. Jan 4, 2010 #5
    Re: Physics help!!?

    The total force is not 650N, that's simply the drag force.

    What other forces act on the sky diver?
  7. Jan 4, 2010 #6
    Re: Physics help!!?

    Thats the only force mentioned in the question - sorry..I need to work out acceleration yes? Do I need to find other forces..? Thanks!
  8. Jan 4, 2010 #7
    Re: Physics help!!?

    Or could anyone just advise me on how I would work out/answer a question thats similar to above..? Then I can apply the knowledge to those kind of questions..... :)
  9. Jan 4, 2010 #8
    Re: Physics help!!?

    excuse me if you have already found it but you need to find the force of gravity pulling him downwards.
  10. Jan 4, 2010 #9
    Re: Physics help!!?

    do you guys in America need to convert your speed of 80mph to SI units of m/s ?
  11. Jan 4, 2010 #10
    Re: Physics help!!?

    I guess it depends on the units in which they want the answer in. Generally,(in my experience atleast) answers tend to be in SI units.
  12. Jan 4, 2010 #11
    Re: Physics help!!?

    we always use si in my class. its easier that way. (especially for conversion
  13. Jan 5, 2010 #12
    Re: Physics help!!?

    Ok..but how do I work out the answer for a question similar to above?!!!! PLease can someone advise??
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