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!

Earth to the Moon power help

  1. Apr 7, 2008 #1
    1. The problem statement, all variables and given/known data
    The amount of energy required to get a spacecraft from the Earth to the Moon

    a. is greater than the energy required to go from the Moon to Earth.
    b. is the same as the energy required to go from the Moon to Earth.
    c. is less than the energy required to go from the Moon to Earth.


    2. Relevant equations

    G= mM/r^2

    3. The attempt at a solution
    I think the answer is c.
     
  2. jcsd
  3. Apr 7, 2008 #2

    Dick

    User Avatar
    Science Advisor
    Homework Helper

    Why?
     
  4. Apr 7, 2008 #3
    wait, i get it now.

    gravitational force is greater on earth so it would require MORe energy to go from earth to moon..
    answer is A.
     
  5. Apr 7, 2008 #4

    Dick

    User Avatar
    Science Advisor
    Homework Helper

    Yes. Though you are oversimplifying a bit. In going from the earth to the moon means you are losing energy to the potential energy of the earth's gravitational field and gaining it from the moon's. Coming back is the reverse. Which potential energy difference is greater?
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?