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: Simple harmonic motion

  1. Feb 13, 2007 #1

    akj

    User Avatar

    Hi i need help with this question. It is focused on simple harmonic equation and the rest of the assignment uses many question which are structure like this.

    A mass of 16kg on a spring of k = 9.0N/m passes the midpoint of motion with a velocity of 2.0m/s what is the amplitutde?

    I am unsure what equation(s) i could use that contains mass, spring contanstant (k), velocity and amplitute or displacement.

    I would be greateful for any help,

    thanks in advance.
     
  2. jcsd
  3. Feb 13, 2007 #2
    You should really show us what you've tried.
    Use the equation relating angular velocity, mass, and k.

    Then take a look at the equation for velocity given by the conservation of energy.

    Remember at the midpoint/equilibrium x = 0.

    Oh, and post homework questions in the homework forum!!
     
  4. Feb 13, 2007 #3

    akj

    User Avatar

    thanks for your response. Are you referring to anqular velocity = square root[(k/m)]?. if so how do i relate this to working out the amplitute?
     
  5. Feb 13, 2007 #4

    mjsd

    User Avatar
    Homework Helper

    instead of trying to dig out which equations to use, why not derive all of them yourself, that way u will understand everything a lot better.
    start with key equation F=-kx = m x'' where x'' is the 2nd derivative. etc. then you will find a form for x in terms of sin/cos ..etc. then using basic relations like ang freq = 2 pi f, 1/f = period etc you can solve for everything. Amplitude will just be the factor outside your sin/cos functions. NB: you have been given some conditions so that you can fix some of your integration constants.
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook