1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Work done by a spring

  1. Dec 6, 2007 #1
    1. The problem statement, all variables and given/known data
    When a 75 gram mass is suspended from a vertical spring, the spring is stretched from a length of 4.0 cm to a length of 7.0 cm. If the mass is then pulled downward an additional 10.0 cm, what is the total work done against the spring force?


    2. Relevant equations
    U=mgh (Don't need the work equation because work = energy)
    U= 1/2 k x^2 (equation for the elastic spring with potential energy.)


    3. The attempt at a solution
    mass = .075 kg
    height = .21 m (.04+.07+.1 = .21m)
    gravity = 9.81m/s^2

    U=mgh
    U= (.075)(9.81)(.21)
    U= .15 J

    I know the answer is wrong because the book says the answer is .21 J
     
    Last edited: Dec 6, 2007
  2. jcsd
  3. Dec 6, 2007 #2

    rl.bhat

    User Avatar
    Homework Helper

    When there is no mass the length of the spring is 4 cm. When a 75 gram mass is suspended from a vertical spring, the spring is stretched from a length of 4.0 cm to a length of 7.0 cm. From this calculate the force constant k, and then calculate the work done. mgh is the work done when the body is falling freely.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Work done by a spring
  1. Work Done by Spring (Replies: 3)

  2. Work done by a spring (Replies: 6)

Loading...