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Calculating deacceleration force

  1. Jun 3, 2009 #1
    1. The problem statement, all variables and given/known data

    An object is moving at a velocity of 28m/s
    The mass is 100kg
    It deaccelerates from 28m/s to 0 in a distance of 5m

    How much force (N) is needed to stop the object?


    2. Relevant equations


    3. The attempt at a solution
    I need help, please! :)
     
  2. jcsd
  3. Jun 3, 2009 #2

    PhanthomJay

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    You can use one of the kinematic eqations of motion to solve for the deceleration; and then use one of Newton's law to solve for the force. Or use energy methods. Please show what you have tried or your attempt at a solution.
     
  4. Jun 3, 2009 #3
    Currently I got a 39,4C fever and have problems concentrating.

    I understand that I probably need to use the f=ma basic formula but what I cant get my head around is the conversion to time.

    Meaning I have the velocity, mass, deacceleration distance, and changes in velocity, still, I cant get my sore head to comprehend how to extract time from it, I´m stuck so unfortunatley I have no formula or attempt to a solution.
     
  5. Jun 3, 2009 #4

    PhanthomJay

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    Yow, you can't do too much with a 103 (degrees F) temp! Get well soon!

    You don't need time; there is a basic kinematic equation that relates velocity with acceleration and distance. For a final velocity of 0, does v^2 = 2(a)(s) sound familiar, where v = 28, and s =5, then solve for a. Take care.
     
  6. Jun 3, 2009 #5
    You are right, I really should leave this for tomorrow instead!

    Thanx a bunch for your help! looks like it solved my problem! :)
     
  7. Jun 3, 2009 #6

    PhanthomJay

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    I might have given you a bit too much help, but while still working with a 39,4, you deserved it.
     
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