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Homework Help: Linear Momentum Algebraic interpretation

  1. Oct 29, 2014 #1
    1. The problem statement, all variables and given/known data
    A light object and a heavy object have the same kinetic energy. Which has more momentum?

    2. Relevant equations
    I am trying to prove this through algebra.
    I don't understand how to show this any help?

    3. The attempt at a solution
    1/2m1v1^2 = 1/2m2v2^2 when m1 > m2

    v1 = v2 squareroot(m2/m1)

    m1v2 squareroot(m2/m1) = m2v1 squareroot(m1/m2)
  2. jcsd
  3. Oct 30, 2014 #2


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    I do not see what is the sense of your last line. What are the momenta?
  4. Oct 30, 2014 #3


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    I suggest you work in the other direction and do not use v as a variable. Instead, solve for v from p = mv and insert this into the expression for kinetic energy.
  5. Oct 30, 2014 #4
    Here's a hint. You do have to use algebra here, but this is only a qualitative question where you have to find the relationship

    ## \frac{KE_1}{KE_2} = constant = \alpha(m_1, m_2) \frac{p_1^2}{p_2^2} ##

    where ## \alpha ## is a function of the two masses. Once you find this relationship, you can answer the question easily.

    Goodluck!!! ;)
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