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 Question

  1. Nov 11, 2004 #1
    the question is A mass of 3 kg is dropped from a height of 3.26 meters above a vertical spring anchored at its lower end to the floor. If the spring constant is 25 N/cm, how far to the nearest tenth of a cm, is the spring compressed?

    alright so the gravitational potential energy is converted to kinetic as it falls which is the converted to elastic as it hits the spring.

    mgh = 1/2kx^2
    3(9.8)(3.26+x) = 1/2 2500 x^2
    x= square root of 2(3)(9.8)(3.26+x)
    ----------------
    2500
    which then leaves (i think)
    x = square root (3.26+x)
    --------
    42.5

    now here's where i'm stuck... i'm not sure what to do next. :s the answer is supposed to be 28.9 cm though... i would be so grateful if someone would help me!!!
    thanks
     
  2. jcsd
  3. Nov 11, 2004 #2

    Doc Al

    User Avatar

    Staff: Mentor

    Good! Now realize that this is a quadratic equation and solve it accordingly.

    And welcome to PF!
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook