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average force question

Discussion in 'MCAT Study Question Q&A' started by ssiding, Dec 14, 2008.

  1. ssiding

    2+ Year Member

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    hey guys can you help me solve this problem from my kaplan workbook;
    A hammer head with mass 500g is moving at 4m/s collides with a nail (m=4g) and comes to a stop in 0.002 seconds. What is the average force acts n the nail during the time?

    a. 10^6 N
    b. 10^3 N
    c. 8N
    d. 8 X 10^3 N
     
  2. AmbitiousMD

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    This is what I did...

    Vfinal= 0 m/s
    V initial= 4 m/s
    t= 0.002 seconds
    Used the equation

    v=vinitial+at

    0=(4m/s)+a(0.002)

    Ended w/ a=2000 m/s

    Plugged that into fnet=ma

    Fnet=(500)(2000)

    And got 1000000 AKA 10^6

    Now, I don't know if when plugging in the m in fnet=ma to add the extra 4 g of the nail.. I didn't obviously.

    Tell me what you're getting.
     
  3. cathyrn

    cathyrn Junior Member
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    I used impulse and momentum...don't know if that was right unfortunately
    F X CHANGE in time = mv

    so F= .5kg x 4/.002 = 10^3
    what is the answer that is given?
     
  4. AmbitiousMD

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    ^ Oh yes.. I forgot.. must convert grams to kilograms.
     
  5. ssiding

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    I don't know the answer. My tutor gave me a set of problems? I will not get the answers from him for another week.
     

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