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!

Finding n for quantized energies

  1. Sep 27, 2009 #1
    1. The problem statement, all variables and given/known data

    A simple pendulum has a length equal to 0.6 m and has a bob that has a mass equal to 0.5 kg. The energy of this oscillator is quantized, and the allowed values of energy are given by En = (n + 1/2)hf0, where n is an integer and f0 is the frequency of the pendulum. Find n such that En+1 exceeds En by 0.010 percent.

    2. Relevant equations

    En=(n+1/2)hf0

    3. The attempt at a solution

    I thought this sounded like a simple algebra problem, so I set .0009(En+1)=En and solved for n after plugging in the equations. I know there is something wrong with this equation because I keep getting negative, non-integer values for n but I cannot figure out what is wrong. Any help is greatly appreciated.
     
  2. jcsd
  3. Sep 27, 2009 #2
    Since my first post, I have tried a revised approach. This time I have En+1=En*1.0001. This gives me (n+1)+(1/2)=(n+(1/2))1.0001. After doing all the algebra, I am getting 9999.5 as my answer for n. Since the question asks for an integer value, I do not know if show input 9999 as my answer or if my answer is just wrong in general.
     
  4. Sep 28, 2009 #3

    gabbagabbahey

    User Avatar
    Homework Helper
    Gold Member

    Your second method looks fine, and I would round 9999.5 up to 10000.:approve:
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook