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Calculated the total time kinematics

  1. Oct 14, 2005 #1
    Here is the problem that am working on.

    A stone is thrown vertically upward with a speed of 12.0 m/s from the edge of a cliff 70 m high.
    (a) How much later does it reach the bottom of the cliff?
    (b) What is its speed just before hitting
    (c) What total distance did it travel.

    I have calculated the total time it takes to reach the bottom of the cliff, but haven't been able to do the (b) and (c) part. Here is what i have done

    I used this formula to compute the time and am getting it right.

    x= x(0) + v(0)t + 1/2 at^2

    0= 70+12t+1/2(-9.8)t^2
    t= 5.2 seconds, -2.75 seconds

    the ans to the c part is 84.7m and b part is38.9 m/s. Please suggest me a hint. Thanks
  2. jcsd
  3. Oct 14, 2005 #2
    Looks like you need to find the maximum height the stone makes it to, for B) and C). Remember at the max height velocity = 0
  4. Oct 14, 2005 #3


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    Gold Member

    And remember that the V0 will be positive in the velocity equation
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