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Homework Help: Finding initial kinetic energy

  1. Jan 29, 2012 #1
    1. The problem statement, all variables and given/known data
    A student throws 0.22kg rock horizontally at 20.0m/s from 10.0m above the ground. Ignore air resistance.

    Find the initial kinetic energy of the rock

    2. Relevant equations
    Ek = mv^2/2

    3. The attempt at a solution
    This sounds INCREDIBLY easy and every shape or form
    Simplying plugging in what I know

    Ek =(0.22)(20.0)^2/2

    Get's me the answer of 9.68
    However APPARENTLY that's the wrong answer
    The answer that I'm given is 44J
    How is this possible? I must have gone completly off track somewhere.
  2. jcsd
  3. Jan 29, 2012 #2


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    Staff: Mentor

    Check your arithmetic. Pay careful attention to the order of operations.
  4. Jan 29, 2012 #3


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    Homework Helper

    Your (red) statement is correct - if clumsily written - it would appear the only problem is when you start entering the numbers into your calculator - not that you should need one for that calculation.
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