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!

Using moon's rotational energy on earth

  1. Mar 14, 2015 #1
    1. The problem statement, all variables and given/known data
    Suppose that some time in the future we decide to tap the moon's rotational energy for use on earth. In additional to the astronomical data in Appendix F in the textbook, you may need to know that the moon spins on its axis once every 27.3 days. Assume that the moon is uniform throughout.


    1. How much total energy could we get from the moon's rotation?
    E = 3.15 x 10^23 J

    2. The world presently uses about 4.0×1020J of energy per year. If in the future the world uses five times as much energy yearly, for how many years would the moon's rotation provide us energy?
    t = 158 years

    3. In light of your answer, does this seem like a cost-effective energy source in which to invest?

    2. Relevant equations


    3. The attempt at a solution
    I'm just curious as to why this would not be a cost effective energy source. If the moon complete one rotation every 27.3 days, and as a result, it provides energy for 158 years, how is that not cost effective?
     
  2. jcsd
  3. Mar 14, 2015 #2

    mfb

    User Avatar
    2016 Award

    Staff: Mentor

    What happens after 158 years?

    How did you get that number? How would you harvest this energy to use it?
     
  4. Mar 14, 2015 #3
    Future energy use = 5* (4.0×10^20)= 2 x 10^21
    3.15 x 10^23/ 2x10^21 = 158 years
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted