Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Using conservation of energy to find spring constant but off number

  1. Oct 29, 2011 #1
    Okay so I think the answer should be 180N/m unless the book is wrong and I got 114N/m. Now if there is a mistake in my work shown in the picture it would have to be the height final or height initial. I am going with height inital is the x initial and the height final equals the x final.(I think this is correct)

    question; a .60kg metal sphere oscillates at the end of a vertical spring. as teh spring stretches from .12 to .23m(relative to its unstrained length) the speed of the sphere decreases from 5.7 to 4.80m/s. what is the spring constant of the spring?
    http://img231.imageshack.us/img231/8118/001ql.jpg [Broken]

    Uploaded with ImageShack.us
    sorry for the work on the back that you can see. any help would be greatly appreciated!!
    1. The problem statement, all variables and given/known data

    2. Relevant equations

    3. The attempt at a solution
    Last edited by a moderator: May 5, 2017
  2. jcsd
  3. Oct 29, 2011 #2


    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper
    Gold Member

    As the spring stretches, the mass is at a lesser height, therefore has less gravitational potential energy, but more potential energy due to the spring.

    You could consider the height to be -x.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook