KE-1/2mv^2 physics question

  1. hi I am new and new to physics i am have alot of trouble with this problem

    mass =1.3kg
    41.5J
    how do i get the velocity

    so far i have it wrote like this
    41.5J=1/2(1.3kg)(v)^2

    but dont know how else to do plz help thanks ron
     
  2. jcsd
  3. The equation KE=1/2mv^2 says that the kinetic energy is equal to half of the mass of the object times the object's velocity squared. So you need to solve for velocity (v). Isolate the v variable using algebra (try to get v by itself on one side of the equation).
     
    Last edited: Jan 28, 2006
  4. KE=1/2mv^2
    41,5J=1/2*1,3*v^2
    41,5J/(1/2*1,3)=1/2*1,3*v^2/1/2*1,3
    63,8=v^2
    sqrt(63,8)=v
    v=7,98 m/s
     
  5. Integral

    Integral 7,341
    Staff Emeritus
    Science Advisor
    Gold Member

    You will find that it is easier to do your algebra BEFORE plugging in the numbers. You have

    [tex] \mbox{KE} = \frac 1 2 m v^2 [/tex]
    then
    [tex] 2 \mbox{KE} = m v^2 [/tex]
    then

    [tex] 2 \frac {\mbox{KE}} m = v^2 [/tex]

    so

    [tex] v = \sqrt { 2 \frac {\mbox{KE}} m } [/tex]

    Now you can substitute in your numbers and arrive at the numeric solution.
     
    Last edited: Jan 28, 2006
  6. thank you for the help i have been out of school 24 years and this is my last semester for my degree thanks ron
     
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