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Calculate the average force exerted on the driver by the seat belt

  1. Dec 17, 2006 #1
    1. The problem statement, all variables and given/known data
    A car is involved in a collision when it is travelling at 24m/s. The driver , of mass 85kg, is brought to rest by the seat belt in a time of 400 ms . Calculate the average force exerted on the driver by the seat belt . Compare this force with his weight , and hence calculate the 'g-force' to which he's subjected by the crash, and comment on the likelihood of his sustaining serious injury.

    2. Relevant equations

    3. The attempt at a solution
    Well, I' use F=m (v-u)/t to find the average force exerted on the driver, am I correct ? Second question , can I use formula of work done to calculate the 'g-force' ? Logically, is it impossible the 'g-force' means the potential energy stored in the car ? Guide me please .
  2. jcsd
  3. Dec 17, 2006 #2


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    F = ma so you are on the right track with the first part. "g-force" just means the ratio of the acceleration to gravitational acceleration, which is the same as the ratio of force to weight. We commonly say a force is "7 Gs" if a force on an object is 7 times its weight.
    Last edited: Dec 18, 2006
  4. Dec 18, 2006 #3
    'g-force' , how 'd i calculate ?
  5. Dec 18, 2006 #4
    He just explained : g force is the ratio of acceleration to gravitational acceleration.

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