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Homework Help: Springs, mass, speed.

  1. Feb 1, 2010 #1
    1. The problem statement, all variables and given/known data
    a 300 g mass vibrates at the end of a horizontal spring along a frictionless surface. if the spring constant is 45N/m, and the maximum displacement of the mass is 8.0cm, what is the maximum speed of the mass?


    2. Relevant equations

    g=Gm/r^2

    3. The attempt at a solution
    do i rearrange the formula to solve for m. so it becomes m=r^2(g)/G. that only gives me the mass tho. how do i solve for the speed??
     
  2. jcsd
  3. Feb 1, 2010 #2
    I don't even know what you're doin.

    Find the acceleration with F_spring=kx and F=ma.

    When is the spring traveling the fastest? You should use (or combine) 3 equations to get your answer. I gave you 2.
     
  4. Feb 1, 2010 #3
    ok so,
    Fspring= 45N/m(0.08m) whick is 3.6N. then arrange f=ma to solve for a, which is a=3.6N/0.3Kg, so the a is 12. then do i use the formula Vf^2=Vi^2 + 2ad. so,i would square root (2)(12)(0.08) to get 1.4 m/s as the maximum speed?
     
  5. Feb 1, 2010 #4
    if "maximum displacement" means the distance from where the spring is uncompressed, to it's maximum compression.. then yes that's right.
     
  6. Feb 1, 2010 #5
    Thank you so much :)
     
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