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How to calculate the height of something by throwing an object off it?

  1. Dec 1, 2011 #1
    I go rock climbing a lot with my BSA troop, and my friends and I can only estimate the height. I want to know the exact height. Considering I do not have a ruler long enough to measure the height of the cliff, I know there is a way to throw an object off the cliff (say, a rock), time how long it takes to hit the ground, and then do some math and then you have the height.

    I want to know how to do the math. Please be detailed with your answer, because I'm 15 and not really a math genius (I'm good, but not THAT good).

  2. jcsd
  3. Dec 1, 2011 #2


    Staff: Mentor

    h = 16t2
    t is in seconds and h is in feet.
  4. Dec 1, 2011 #3
    Make sure if you use mark's equation that the rock is either dropped or thrown straight ahead.
  5. Dec 1, 2011 #4


    User Avatar
    Gold Member

    BTW, there are other ways that might have less error than estimating a time of a second or two.

    You can figure out how far you are from the base of the cliff and use trig to calculate its height.
  6. Dec 1, 2011 #5


    User Avatar
    Science Advisor

    Damn you beat me. :frown:
    But yes, trig is how it has always been down in the past. And we have GPS now, so it's easier too.
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