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Find how long does it take to hit the ground from a car off a cliff

  1. Oct 17, 2011 #1
    1. The problem statement, all variables and given/known data
    A 500kg car drives of a 400m cliff located on the surface of the earth how long does it take to hit the ground

    2. Relevant equations

    F=ma
    F=mg
    d=1/d at^2

    3. The attempt at a solution

    i first did f=mg to find f
    then i did f=ma converted that to find a
    then did 1/2 at^2 converted that 2
    d x 0.5 / 9.8 then i root it to find t
    but i got the wrong answer, the answer is 9 seconds can some one tell me what i did wrong
     
    Last edited: Oct 17, 2011
  2. jcsd
  3. Oct 17, 2011 #2
    You're looking for an answer in metres, how far something is, is distance.

    So the answer can't be 9 seconds. You already have how long it was in the air.
     
  4. Oct 17, 2011 #3

    NascentOxygen

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    Staff: Mentor

    You are interested in its travel in the horizontal. The car experiences no acceleration horizontally.
     
  5. Oct 17, 2011 #4
    i been studying all night and its rly late i was combining 2 questions in 1 cuz i am soo tired i fixed the question now lol
     
  6. Oct 17, 2011 #5

    NascentOxygen

    User Avatar

    Staff: Mentor

    This is an entirely different question, now. Your question has become: how long does it take something to fall 400 m, starting from rest.

    What equation will you use for that?
     
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