1. Limited time only! Sign up for a free 30min personal 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!

Equations of motion

  1. Apr 30, 2014 #1
    1. The problem statement, all variables and given/known data
    A particle of mass m moves freely in space in the x direction.
    (a) Derive equations of motion for the following operator expectations:

    <x(t)>, <p(t)> , <X^2(t)>,<P^2(t)>

    2. Relevant equations

    3. The attempt at a solution

    baah I dont even know....
    I guess we'll start from the equation of motion d<x(t)>/dt = 1/ih <[X(t),H]> + <dx(t)/dt>
    but how do I find the average of dx(t)/dt?

  2. jcsd
  3. Apr 30, 2014 #2

    Simon Bridge

    User Avatar
    Science Advisor
    Homework Helper

    You know the definition of an expectation value for an operator don't you?
  4. May 1, 2014 #3
    Yes but I'm not given x(t) so how would I find it's time derivative to average?

  5. May 1, 2014 #4

    Simon Bridge

    User Avatar
    Science Advisor
    Homework Helper

    x is an operator.
  6. May 1, 2014 #5
    OHH I see what you mean, so operate on the free particle wave function THEN find derivative?

Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted

Similar Discussions: Equations of motion
  1. Equations of motion (Replies: 2)

  2. Equation of Motion (Replies: 11)