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: Spring an crate question

  1. Nov 4, 2006 #1
    A 1.5kg crate falls from a height of 2.0m onto an industrial spring scale with a spring constant of 1.5 X 10^5 N/m. At its greatest compression the reading on the scale is:

    My work:

    mgh= PE
    (1.5kg*9.81m/s*2.0m)= 30J
    The potential energy of the crate is 30J
    The Force of the crate is 1.5kg* 9.81m= 14.75
    Would the force of the crate be equal to the force of compression

    Thank you
  2. jcsd
  3. Nov 4, 2006 #2


    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    You missed the spring part. The weight of the crate is 14.75 N, but the force on the spring is, per Hookes law, F =kx.
    One way to solve for x is to use the conservation of energy principle, noting that initial energy (which is just potential) is equal to final energy (which is just the spring (stored) elastic potential energy , 1/2kx^2. (There is no kinetic energy in the initaial or final case). Try to solve for x, then F.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook