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Homework Help: The max height the body reaches when this body is thrown verticaly upwards

  1. Nov 28, 2009 #1
    1. The problem statement, all variables and given/known data

    What is the maximum height that the body reaches when thrown vertically upwards from the surface of the Earth at a velocity of 5km/s, if we neglect the impact of the atmosphere? The radius of the Earth is r= 6400km; the acceleration of gravity on the surface is g = 10 m/s².

    2. Relevant equations

    KE= mv²/2
    PE= mgh

    3. The attempt at a solution

    KE + PE = PE’

    (mv²/2) – (mM/r)G = -(mM/r+h)G

    F(gravity)= mg
    f = (mM/ r²)G

    mg = (mM/ r²)G
    g= MG/ r²) → MG = g r²

    h= [g r² / rg/r – v0²/2] – r
    h= 1553.4 m

    Are my calculations correct?
  2. jcsd
  3. Nov 28, 2009 #2


    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    Your answer is too low by a factor of 1000. Redo the calculation and pay attention to the powers of 10 that you put in. Be sure to convert all kilometers to meters.
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