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Homework Help: Motion & Projectiles Help Please

  1. Mar 4, 2012 #1
    1. The problem statement, all variables and given/known data
    A night somebody pushes a derelict car horizontally off a 45m high cliff top at 2.0 ms^-1.
    (a) How long does it take to hit the ground? (g=10ms^-2)
    (b) How far from the base of the cliff does it land?


    2. Relevant equations
    The answer to (a) is 3.0s and (b) is 6.0m


    3. The attempt at a solution
    For (a) I tried s = ut +.5at^2. Hence 45 = 2t+.5(10)t^2 but the answer was not correct.
     
  2. jcsd
  3. Mar 4, 2012 #2

    Nugatory

    User Avatar

    Staff: Mentor

    That's because you mixed a horizontal speed with a vertical acceleration.
     
  4. Mar 4, 2012 #3
    Ah ok I got it now, thanks :).
     
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