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Homework Help: Acceleration given velocity and distance

  1. Oct 4, 2008 #1
    1. The problem statement, all variables and given/known data
    A car traveling at 90 km/h strikes a tree. The front end of the car compresses and the driver comes to rest after traveling 0.86 m. What was the average acceleration in g's of the driver during the collision?

    2. Relevant equations

    3. The attempt at a solution
    The acceleration in m/s/s is -363.37 but I tried dividing by 9.8 and I got -37.05 g's but evidently thats wrong. I'm not sure what I'm missing here, I converted the km/h into m/s/s then got the correct acceleration then devided by 9.81. Is there a rule that I didn't use? Is there a limit on negative gs?
    Last edited: Oct 4, 2008
  2. jcsd
  3. Oct 5, 2008 #2
    You are right, the acceleration is -363.37 m/s/s.

    I'm not a hundred percent sure, but I think -37.08 g's is actually correct. Because if one g is worth 9.8 m/s/s, and you had positive 37.08 of them, your acceleration would be in the positive direction. But it's not... so I see no problem with having a negative number there.

    Is there another reason you think -37 g's is wrong?
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