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!

Conveting Mass Into Energy Problem

  1. Jan 28, 2007 #1
    1. The problem statement, all variables and given/known data
    The annual energy requirement of the USA is of the order [tex]10^20[/tex] J. If we could find a 100% efficient process that could change matter into energy, how many kilograms of material would be needed to meet this requirement?

    2. Relevant equations
    [tex]E = mc^2[/tex]

    3. The attempt at a solution

    Well, i simply sub [tex]10^2^0[/tex] in to [tex]E = mc^2[/tex]
    And i obtain, [tex]\frac{10^2^0}{(3.0*10^8)^2}[/tex]
    then [tex]m=11,111.1111[/tex]

    Is this correct? It looks to me like too simple a question, since this is the last question of my tutorial.
    Last edited: Jan 28, 2007
  2. jcsd
  3. Jan 28, 2007 #2
    It might have just been a question put in to make you think about the possible consequences. But theres a slight miscalculation - you're off by one decimal place: ~1,111 Kg. Whats so special about this? Dividing by 365 to get the daily rate, you arrive at the conclusion that to support the energy needs of the USA on a daily basis would require 3 Kg of matter to be completely transformed into energy. Maybe you could compare it to the magnitude of fuel used nowadays? Just food for thought.
  4. Jan 28, 2007 #3
    K, thanks for the help.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?

Similar Discussions: Conveting Mass Into Energy Problem
  1. Mass & Energy (Replies: 1)