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Homework Help: Net Force of car

  1. Feb 18, 2009 #1
    1. The problem statement,

    A driver wearing a seatbelt decelerates at roughly the same rate as the car itself. Since modern cars have a "crumple zone" built into the front of the car, the car will decelerate over a distance of roughly 1.0 . Find the net force acting on a 70-kg driver who is decelerated from 21m/s to rest in a distance of 1.0m .


    2. Relevant equations

    I am having trouble setting this problem up can someone help

    3. The attempt at a solution
     
  2. jcsd
  3. Feb 18, 2009 #2

    mgb_phys

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    First you need the acceleration.
    They decelerate from 21m/s to 0 in 1.0m. Which motion equation only has speed, acceleration and distance ?

    Then you need the equation the relates force, mass and acceleration.
     
  4. Feb 18, 2009 #3
    Is d = vt + (1/2)at^2 the right formula if so we do not have time
     
  5. Feb 18, 2009 #4

    mgb_phys

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  6. Feb 18, 2009 #5
    ok so i would use v^2= Vo^2+2aDx
    That woud give me acceleration and then I would use F=ma and use the mass of driver and the acceleration calculated to find the net force
     
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