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Homework Help: Applying newton's laws to traveling car

  1. Feb 18, 2008 #1
    1. A car traveling at 62 km/h hits a bridge abutment. A passenger in the car moves forward a distance of 57 cm (with respect to the road) while being brought to rest by an inflated air bag. What magnitude of force (assumed constant) acts on the passenger's upper torso, which has a mass of 46 kg?

    2. Relevant equations

    F= m*a

    3. The attempt at a solution

    I know its the force of the car= - the force of the bridge. But I am not exactly sure how to put into that equation the distance the person traveled and the velocity of the car
  2. jcsd
  3. Feb 18, 2008 #2
    Forget the car, forget the bridge, hell, even forget the person. All you need to know is that a mass of 46Kg was decelerated from 62 Km/h to 0 over a distance of 57cm.

    You can use constant acceleration formulae to determine the acceleration, then from that determine the force with F = ma.
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