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Math Help - Finding the speed of an object on Mars

  1. #1
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    Finding the speed of an object on Mars

    The equation for free fall at the surface of mars is s = 1.86t^2*m with t in seconds. Assume a rock is dropped from the top of a 250-m cliff. Find the speed of the rock at t = 1.5 sec.

    I know it's probably simple, but I'm not too sure sure of my answer. Thanks for your help.
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  2. #2
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    How, in general, do you find velocity from the displacement?
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  3. #3
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    Well, velocity would be the derivative of position. So v = 3.72t I'm guessing. I have no idea if the m goes away, and if it does, what do I do from there?
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  4. #4
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    The m is a constant multiplying everything else. It can't go away. Without any further information (like a calibration point), you will have an m in your final answer.
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  5. #5
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    Ok, so far I've come up with v = 5.58m. I know that speed is the absolute value of velocity so would the answer just be 5.58m?
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  6. #6
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    Yeah, that seems correct. It's interesting that without knowing how much time it takes to reach the bottom of the cliff, knowing the cliff height is absolutely useless to you.
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  7. #7
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    Thanks for the help. ^.^
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  8. #8
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    You're welcome. Have a good one!
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