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Homework Help: I think this is another momentum question

  1. Nov 21, 2006 #1
    i really have no clue what to do in this problem since theres a measurement for the dent...what formula am i supposed to use for this????

    4. During an autumn storm, a 0.012kg hail stone traveling at 20.0m/s made a 0.20 cm deep dent in the hood of Darnell’s new car. What average force did the car exert to stop the damaging hail stone?
    so far i understand:
    mass= .012kg
    velocity= 20 m/s
    and then theres the .20 cm deep dent but i dun knoe whats that need for?
    Last edited: Nov 21, 2006
  2. jcsd
  3. Nov 21, 2006 #2
    You could probably use momentum or kinematics, but the work-energy theorem is a better place to start
  4. Nov 21, 2006 #3


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    Can you describe, in detail, the trajectory that the hailstone has travelled, and everything that's happened to it?
  5. Nov 21, 2006 #4
    Would it be right to use v^2=-2*a*s to find the acceleration and then force

    If you do not know v^2=u^2+2as try to derive it using:


  6. Nov 22, 2006 #5
    But its a lot easier with energy. W=-KE0
    Everything you need to plug in is given, using acceleration is reproving the work energy theorem with kinematics.
  7. Nov 22, 2006 #6
    We had a similar problem in our physics class, but my physics teacher says the solution is incorrect.
    1) How long was the impact, if it traveled .2 cm at 20 m/s? (This is the part that is incorrect.)
    2) Ft=m(v_2-v_1)
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